I was attempting to change seats in my rover, from the mining crane to the driver's seat. When I exited the Crane I ended up under the vehicle; I didn't think much of it as I have had this happen without problem before. Unfortunately, when I got into the driver's seat from under the rover it and its trailer decided to freak out and are now floating at, I presume, the center of the planet with me. The rover seat being a save point I think the problem is apparent.
Yall might need to attach the exit point of the crane seat to one side or the other of the rover base rather than the crane itself as the current setup is really touchy.
I noticed when I got out of the vehicle that my astronaut fell up until he came out in a cave; If yall can mirror this for vehicles it might help a bit.