Like Jello, there’s always room for Trump.
My own modest proposal along the lines of the OP’s thoughts, but much much better (Of course; cue oh-so-modest bow. 
).
The plan:
Mods create a new category named “all things trumpy”. Block further topic creation there by anyone other than mods. Mods post a sticky locked topic that the category / topic rules are the same as the Pit. Mods also post a new topic there called “all things trumpy”.
All other threads & posts, including those in P&E, are prohibited from discussing trump, trumpism, or trumpists, no matter how tangentially. All such posts must go into the great omnibus of hate proposed in my prior paragraph. Anyone violating the above will have their posts dumped into the monster trump thread and have a nasty mod note appended to their Permanent File. Or given a Warning for repeat offenders.
All existing threads with a trump tag are closed. No discussion, just killed outright.
Please stop trying to make work for us.
Also, everyone concerned about this please use the tag. Think of trump as a forum for all things trump to look at or ignore. That is a big part of the tags.
I’ll use my macro:
Steps to Mute a Tag or Category (Forum)
Click your user icon next to the menu.
Click the last Icon for Profile
Click Preferences
Click Tracking
The lower right hand box is for Muted Tags.
Enter tru and you’ll be prompted for trump. Click trump.
Click Save Changes
.
.
To Ignore a user from Preferences
Click your Profile Avatar in the upper right hand corner
Click the Profile icon (at the bottom of the icons)
Click the 
Gear icon for Preferences
Click the Users menu item
Click Add button under Ignored
Type in the username
Select a Timeframe, which is a pain on a phone.
Click Ignore
By definition, a “modest proposal” is a not-serious one.
Of course the right answer is just as you suggest: want a trump-free SDMB? Mute the trump tag and you’re 99.44% of the way there. Viola.
Tag muting is amazing. I only have a few tags muted but it changes the whole board. Tags are one of the best features of Discourse IMO.
Probably oughtn’t raise my standard observation, as it seems unwelcome and likely to result in me being called a troublemaker. But I fail to see the clear line establishing why some threads can/connot be split/joined, and why it is too much work to do so for some threads but not others.
But I’m sure my ignorance is mine alone.
I’ve found myself entering identical info in 2-3 threads lately - often in different fora. (Some of the best info IMO is taking place in the Pit. Other discussions are in FQ and GD.) If I feel up to it, I have linked the other threads. But not always.