I've been investigating and experimenting with SDB files a bit and I think I found the problem with the "imperial ship flying like a UFO" thing I was trying to do. If you look at this, you can see it's definitely possible to give objects animations meant for other objects:
That is the big hovering UFO flying around with one of the little UFO's animations. Both of the SDB files for these UFOs have one "bone", but the imperial ship I was trying to use has 2, and I believe that was the problem. SDB files can be modified and I've played around with them a bit to try to get character models to work properly with different animations, but I think the pirate ship from Pirate Skull Pass only has one bone anyway so I should be able to get that to work and fly around the sky, which would be pretty awesome if this ghost pirate track is happening
Also, I put the car building garage behind the garage door of the test track:
The collision of the normally-empty room behind that door actually fits the size of the garage model really well.