So here's what I use...



It is an 11 Inch Adjustable Friction Arm that I picked up on Amazon for about $15 bucks I think. It is used in photography, but I mounted it to the top of my spray booth. For painting hulls, I cut and drilled a piece of 1" dowel and threaded a 1/4 20 stud in one end, and epoxied a rare earth magnet at the other end.



Yea, I countersunk the magnet to get a better hold on the magnet, those suckers are strong.
Then I epoxied a piece of sheet metal to the inside of the hull,

and then threaded the dowel into the arm...

...and now I can place the hull into almost any position...



For turrets, I made a different bracket out of a part that came with the arm, a piece of scrap metal, a couple of nuts, and a bolt with a small rare earth magnet epoxied to the end...




...and now with another piece of sheet metal epoxied to the inside of the turret...





And that's my rig!
Now for the disclaimer, it can be a little frustrating to get used to at first, as the joints have to line up with a slot to make deep bends in them, but with a little patience, and experience, I find it works great. One thing to watch out for is those MAGNETS! they are so powerful, they can snap really hard to the metal glued to the model, and as a result, some small parts can pop off (especially PE) if not secured well. Try it on a practice kit first, and experiment with different size magnets.
I hope this can help someone, it has really allowed me to get much better with my airbrushing, especially for detail work, since I can be much steadier using both hands on the airbrush.