Fully customizable caravan in parts selector, you can remove any part. 16 options for wheels in 6 sizes and 3 tire options for each on average. You can remove the roof and make it convertible, or have only 1 wheel on it, etc.
That's a huge list. Beware of the maximum slot number of about 250 though. Ran into this once and it was such a bummer... Unless the devs patched this already but I doubt it.
I had no idea that's a thing, but well, not my problem if someone decides to use the caravan on the Gavril Vertex or something, I'll note this in the mod description on repo
It's a per vehicle basis from what I could tell in the past. 250 slots per vehicle. It's a lot until everything's modular.
The common folder technically isn't a vehicle so it's completely dependant on what vehicle the common parts are used on.
What exactly happens when the limit is reached? I've added as much stuff as possible to the Gavril Vertex including the trailer, using the parts that have the most slots, and so far I only reached the flexbody limit (which makes some parts invisible)