So what seems like ages ago now I posted in the support forum asking how I could save the locations of vehicles in game. The answer was helpfully provided by gigawert. While this was pretty much what I wanted, there was still no way to save the rotation of a vehicle - or so it seemed. Today I found out how to do that by accident. I was rebuilding my car bowling alley after I accidently deleted it, only this time I decided to put more time into it than before. I arranged the first caravan vertically, resting the rear on a small ramp. Then I made this into a prefab. I don't why I did, I could just as easy copy and paste it, but I did - and it turned out to be a good thing because that's how you can save vehicle rotation, by making them into a prefab, the one caravan that I didn't make into a prefab spawned horizonataly and fell to the ground. Maybe everyone already know this, but there - have my little story anyway while I enjoy vehicles not spawning inside rocks/trees because they've rotated into them. Hopefully this helps someone.
Uhm, never had problems with that tbh. You just have to make sure you are rotating the vehicle with the editor (not driving and parking it, because then it will not register your rotation when saving)
Maybe I'm just mad or incompotent (both), I could never seem to get the rotation bit working - even rotating them with the editor.