x2, I think it will be fine. If the VX was unibody, maybe a concern but... Either way, I like the idea, but to put it into practice I think you need tube doors and you should replace the rear door. You might notice the exhaust fumes wafting up when you are at stop lights. That alone is reason enough to put the rear door back on.
The VX is kinda a hot box in the summer, especially for those of us with Ebony VXes, so I definitely understand the desire for an open air 4x4! I want to build a unicab Trooper RS at some point in my life.
Bart