A bottle of scotch: sounds like you’ll need it.
How about deviled eggs?
Huh. Ignorance fought.
And I did know everything had to be prepared specially, and I know that shellfish are a no-go, and some animals (something to do with what kind of feet they have?) are totally off as well. I just have never eaten with anyone keeping kosher, so all I know is from pop-culture and very faint memories from church as a child learning comparative religion.
Would you kindly explain the ‘mar’it avin’ phrase for me also? I’m guessing something along the lines of either “better safe than sorry” or “avoid the appearance of evil.” 
As for the OP: I’m voting you stop at the grocery and get them a nice box of fresh clementines for after dinner.
Something I just thought up right now. Candied yams made with simple syrup infused with fall spices. I’m thinking you could boil the yams in spiced water. Make the simple syrup with a little brown sugar and a little regular sugar and then let the boiled yams bake in the syrup. Add raisins. Or mash. Are marshmallows kosher?
Some marshmallows are, if they’re made without animal-derived gelatin.
As an observant Jew, I say “huh?”
As has been said, I can see either no meat or no dairy, but not both. I can also see just not trusting somebody who is not Jewish to prepare kosher food. In that case, you lie and say something like ‘Bring nothing. Your company is enough.’
If you do go with a flask, here’s a list ofkosher liquors
Liquor is an excellent idea!
I make this cranberry chutney every year for Thanksgiving, and it is always a big hit. I’m not sure I’d want to eat nothing else at Thanksgiving, but it does have the advantage of moistening dry turkey very acceptably.
Okay, on the one hand, ignorance fought. On the other hand, the main idea is for you to take that recipe and make substitutions to make it fit the requirements; surely you can come up with a substitution for 9 slices of bread. (Of course, if it looks nasty to you, it’s not worth that effort).
A few years ago I was looking for some recipes for Thanksgiving, and someone sent me this list
of side dishes from the NY Times.
They are all vegetarian, so there should be plenty of safe things to try.
Good luck.
-D/a
What about whipped sweet potatoes? No flour or butter, so you can’t have a streusel topping, but still delicious and filling. You could top it with walnuts tossed with spices.
Here’s my advice as someone who is also allergic to gluten - don’t expect your first Thanksgiving to be very good. You’re still sorting things out, and it really does take time to get the hang of things.
Make some kind of simple side dish to take. Don’t eat much and stick to simple things. Will the turkey be stuffed? Will it be baked in a pan of dressing? You may not get to eat any turkey at all.
Eat plenty before you leave on that three hour drive. Bring something to eat in the car right before you arrive. Maybe have a snack in the car after you leave.
Then, to make it up to yourself, have a really wonderful meal the day before or after Thanksgiving.
Next year will be much better. You’ll have the hang of things, your family will be starting to get the hang of things. Also, gluten free food just keeps getting better.
Kosher delis must have all sorts of snack trays or fruit salads or such that are parve (neither meat nor milk).
Kinda. “Mar’it ayin” translates as “what it looks like to the eye”. When you (if you’re a Jew) pass your Jewish neighbor sitting at a table eating a cheeseburger, you don’t stop to investigate whether the meat in the cheeseburger is turkey or beef. What it looks like is that he is transgressing. So the principle says if it looks to a casual Jewish observer that you’re transgressing, then you are.
Looking at the host’s comments in the OP, it doesn’t seem like they really need or expect you to bring any food.
Given your limitations and those of your hosts, I might try to find a gluten-free cornbread mix to make cornbread or a cornbread dressing.
If you need to make something easy just to have something to bring, you might just want to make some green beans or something along those lines.
Normally a dessert is good for a guest to bring, but I’m not sure what you could make that would be gluten-free, dairy-free, and kosher.
Given all the restrictions flying around I don’t think it would be unreasonable for you to ask that the stuffing not be cooked inside the turkey.
Is there a Wegmans in their town? Call ahead, order something and pick it up. Actually, their local grocery store likely has something kosher and tasty, but Wegmans is my usual go-to.
We have a huge box of kosher salt that we use in cooking. I’d buy one, bring it, hand it to the hostess, and act normally from there.
I’d bring a coupla Vitamin V’s to go with the flask, as well.
Why not volunteer to provide the drinks? A few nice bottles of wine and a selection of different fruit juices. And let them handle the complexity of the food
I bought a box of kosher salt and it had a recipe on the back.
For salt crusted shrimp.
I don’t think I’ve ever even met a practicing Jew and I knew that wasn’t kosher.
I have no real suggestions for Thanksgiving dinner, but I did want to point out that not all chicken broth has gluten in it. Home made broth definitely does not. You might try making your own once a month when you have time and freezing it in 1 cup portions. (I like to pressure can mine, but that’s more involved.)
A nice vegetable side dish would go over well. Look for something that works well served room temperature and then you wouldn’t have to fight for space to warm it in the kitchen. Just keep it safe temp on the drive and let it come to temp once you get there.
IME, if they truly keep kosher, they won’t want you cooking in their kitchen at all (unless maybe if they know you really, really, really well). It’s too easy to screw something up that would require re-kashering the kitchen.
And bringing any treif food into the kitchen is right out, as well. IIRC, especially out is heating/re-heating food, or any liquids. Even veggies can be complicated, depending on how adherent they are.
I’d agree that your best bet is to plan to feed yourself before and afterwards with a special dinner on a different day. If you really feel that you must take something, go with a purchased kosher fruit or veggie tray, or take some nice kosher wine.