What kind of protective gear are you allowed to wear on uniform while riding a motorcycle?

On Guam Naval and Airforce bases, you could wear any safety protective gear. It is encouraged to use safety gear, you are required on base to wear a helmet, reflective vest and eye gear, as well as certification of going through the MC safety class, provided by the military.

Pros and Cons? Plenty. It depends on where you fall on the subject. I have had Wing Commanders (Wing and Vice Wing at the same time once! The salad bowl days of riding in uniform!) who actually rode, and have heard of commanders/leadership that treat riders like second class citizens. A potential safety statistic looking to happen and a hazard to promotion

By DoD regs you can wear chain mail and a bomb suit if you want, but you have to wear a minimum amount of PPE as a military member on a bike, on and off duty. On and off of the installation.
-Helmet (DOT approved. SNELL Memorial Foundation certification is better.), windshield or glasses/goggles, gloves, long sleeves, boots or over the ankle shoes (I think is the wording), contrasting colored clothing (Contrasting to what? Never really got that one. I understand the intent.), reflective at night gear and pants. Some bases or commands dictate additional gear. Reflective gear for daytime. Some require glasses/goggles in addition to a windshield do to low heights or inadequate protection. Jackets vs. long sleeves. Boots only. They can add to but not take away from this. All of that is from memory. If I missed something I sure someone will fill us in.

The Basic MSF course or equivalent is the minimum required to ride on DoD installations. I think the Army makes you take it every 3 years and mandates a crotch rocket (Sport Bike for you purists! LOL) course in addition if that is your ride. Local safety briefings are usually given to ensure you know the drill.
Since you are Army, this is your bible.
Army Regulation 385-55.
Unless the DoD reg (6055.4- DoD Traffic Safety Program) changes there isn't usually too much to change in the service version.

All that PPE, yeah, NOT part of the uniform. DA 670-1, AFI-362903 or other service uniform regs tell you what to wear and how to wear it. MC gear is to be worn on the bike. Lots of guys wear it all from the bike to the building for convenience. Especially the helmet in lue of cap/cover. So you take it all off and put you head gear on.
Hopefully that answered any questions you might have had. Whether you are new to riding, or an old pro, remember that cars don't see you. Those that do will still challenge your right to the lane. They will run you off of the road. Keep your head on a swivel and have fun.

You can and should wear everything you can