Won’t the aluminum foil rip and blow away the first time he gets up to freeway speed?
OP, Ii sent a link to the thread to my nephew. If he doesn’t join the board to respond his own self, I’ll pass along his thoughts.
There is no way to reliably answer this question, I think. It sounds like you’re imagining that the law is constructed such that the legislature, courts, et cetera need to lay down a specific algorithm by which you can figure out reliably whether your car is or is not legal, and if it is, then there’s nothing anybody in the judicial system can do about it.
Doesn’t work that way. The legislature just says, at the most basic level, that your car has to be safe, both for you as well as for any passengers or other people on the road. To some degree they will publish guidelines as to what is and is not considered safe, and it’s certainly advisable to follow them to avoid trouble. (You can just call the DMV, by the way, and ask them questions.)
But in the end, it will be up to a Calfornia cop to decide whether he thinks your car is safe or not, and then up to a California judge to make the decision. They don’t need to say in advance what the standards are, or even justify it to you afterwards. About all they need to do is make their decisions sufficiently non outrageous that their peers and superiors (e.g. other cops, or other judges) won’t overrule them.
So just ask some people you know, focussing more towards the middle-aged and square population that is most likely to be wearing a badge or black robe. (I would be surprised if your survey here of SDMBers is a reliable sampling.) If a nontrivial fraction of your sample say the car looks vaguely unsafe, then it’s just a matter of time before a SD cop thinks so, too, and a state judge agrees with him. (The plus side is that unless you have specifically violated some aspect of the CVC, you’ll likely just be ordered to change things, not pay a fine or be conviced of anything.) You can probably judge how long it will be before your projects comes to an end by the number of people in your focus group who are concerned. If the number if low enough, your odds of getting away with it for quite a long time are probably good.
In that case, there’s no reason not to press forward – but I would advise having a Plan B lying around for how you’re going to immediately comply with an order that tells you to restore the car to a “normal” state, because if you get ordered to do so you’ll not be allowed to drive the car until you do. Not having any car to drive in California can be a real drag – you won’t want it to go on for long. So have a contingency plan.