With the increased random spawn area & the removing of hiding spots around those spawns, the GV camping is much more difficult than it used to be & because of that spawn camping has decreased considerably. I'm happy with it the way it is but I suppose it could be made even more difficult for defenders.
You have to address the question, at what distance are you "spawn camping" vs. "defending"?
If they did anything I would say increase the size of the spawn more & make it a rectangular spawn instead of a circular one, or even a horse shoe shape, or several smaller circular ones separated by a good distance in say, a clover shape or like the club on a playing card.
Anything that puts the defending GV's at risk of being caught with enemy GV's spawning in front of & behind them at the same time means the playing field has been evened out.
As far as turrets disabled, they already are until the AC gets off the ground. If you made GV's that way (M-16's & Osties) you would be in effect, crippling them; it's hard enough to hit anything when your sitting still! Supplies really have to be available from a motionless state because that's the nature of the beast, if you made supplies only dispensable from vehicles in motion, then that would mean all troops would have to be air dropped, no more landing & letting them run. No M-3's parking in a hiding spot & letting their troops out as enemy IL-2's & Hurri's circle overhead cutting their engines periodically to listen for GV's. It seems to me that would change the dynamics of the game in a negative way.
I'll say it again, I like it the way it is. But I have heard some ideas that sounded great in theory....not sure how they would work in practice though.