I've seen them done before with warthogs. But I can't get it to work on a floating platform. When I exit it the warthog goes through the bottom!
What? You're going to have to be a bit clearer on what you want if you expect an answer. I'm guessing you meant something along the lines of how to phase a Warthog Turret through the ground. All you have to do is spawn a platform (or just use the ground), and place a Warthog on it. Then, place another platform on top of the warthog, so that it covers all of the Warthog's body but not the turret. If done correctly, it should be impossible to enter the Warthog through the platform, but the turret should still be usabe. Hope I've been of some help.
I'm not sure about how to do this with a Warthog, but could you just use a Shade Turret? It is the same basic principle, but it doesn't replace a Mounted Machine Gun, if thats what your going for.
I want the MG turret cuz it hits instantly cuz its supposed to be a Light AA gun (It ain't called Light Anti-Aircraft gun for nothing) but I can do it but the turret is always on an angle when it spawns or the warthog always flys through the 5x5 platform! Do I need a thicker platform?