Even if you just have one door that needs finishing, do yourself a favor and build a rotisserie. A screw is the pivot. Make the bars that you screw to the ends of the door some narrower than the door thickness. These are something over 30 years old. I don't bother to keep stretchers for them, but just use whatever is laying around.
Anyone can spray like an expert when the surface is horizontal. With these, you spray one side, let it tack up, and spin the door over to do the other side.
I have enough of these to do a whole house full of doors, but was only painting two this evening.