I think the lack of car mods is because this game is called kerbal space program. Also more generally, mods that only do one thing (pre-designed rovers, spaceships, etc) tend to not be as popular or useful as modular part packs.
Eh, I know some people have built their own crawlers with rover wheels and structural panels and a large number of struts.
Also, I'm pretty sure launch clamps can't be physically moved.
Just as a heads up, a large portion of the community ISS mod (I think all the soviet parts) was done by Bobcat, and he was disappeared a long time ago, and everything he made is all rights reserved. So you could either find a replacement for those parts or make them yourself.