Range Control will not allow current US military issue uniforms to be worn aboard PPMR. Cheapest easiest thing for anyone to do is good old WOODLAND BDU for green (maybe an investment of $20.00 for top and bottom) or 3 COLOR DESERT DCU for tan. (Again easy to find at any surplus store) or get a tan non-nomex flight suit for $20.00.
Active duty, reserve, and Guard service members can wear they're issue uniform. Game control will figure it out from there. Worse case all service members can roll around with myself and my Soldiers in the side by side.
Uniform requirements equals base layer clothing - pants/trousers, coat/blouse, and cover/cap/hat. Your gear color is up to you. I recommend not wearing all black, besides looking retarded you'll die from the sun.