What attribute controls how high a hover vehicle hovers? I've tried several modifications, but to no avail; the vehicle always seems to fly too high above the terrain.

yea i was wondering that too. There's a hover hieght option in the odf, but it doesnt really do anything. I think it requires either making some modification to its collision spheres in its MSH with XSI and/or the SpringBody section of the vehicles odf.

Try messing around with the AddSpringBody section.

Example: Translation:
AddSpringBody = "<x> <y> <z> <scale>"

xyz = location of the spring body from the center of the model located at 0,0,0.
scale = size of the spring body(in meters?)

A spring body with a smaller size should lower the height.

That works wonderfully! Thanks!