Unless things have changed since beta - vehicles dropped from aircraft which land on invalid points are deconstructed after a sec or 2 (just like parking too close to vehical pad or doors). Invalid points included any wall, catwalk, roof, etc.. (In Beta. I dropped an ant perfectly on the wall and thought to myself "cool I can drive around the wall" and before I could move, I suddenly dismounted the vehicle and watched it deconstruct). So I don't hold much hope that you can drop vehicles in odd places - would create too many problems to deal with. Easier to deconstruct them and drive the point home that this is a no-no, so don't bother trying. Dropping vehicles on the courtyards of bases with shields is entirely possible however.
