What degree of driveshaft angle is ok for the rear? How thick of metal do I need for my bellypan? Do I need to run a anti wrap bar on the rear?

I used 3/16 for the belly pan.

Maybe 90 to 120 degrees on driveshaft angle.











Just kidding.
I am only guessing here and my angle is bad. I am thinking 25-30 degrees on mine and so far so good with TG creeper joints.

Are you running the trailgear driveshafts?

with a trail rig you can always point the pinion even steeper and make it a broke back style...

Check out BillVistas driveshaft guide, has worked great in my rig all season.

My belly pan is 10g aluminum sheeted with 3/8" slick plastic stuff. Lots of bracing running between the frame rails.

I run 1/4" plate for my belly pan. I have a pretty easy DS angle. like 20-30*(Short Trans). Antiwrap bar is a worth while mod.

Are you running the trailgear driveshafts?

Yes

I don't run a belly pan at all. I just have a tubular guard that bolts on the bottom of the transfer case similar to the one that FROR sells. I have never had a problem as a result of this and it saves a bunch of weight.
As far as your driveline angle. It depends on what drivelines you are running. IFS front drivelines will take more angle than others. So will a CV joint.
You can tilt the rear pinion up and that will help on you rear angle, but you will have to run a CV if you planning on going fast as it will vibrate.
Flat bellys are way over rated. You can tilt your trans down a couple of inches and that will help.

You don't need a rear traction bar. It helps with rear spring wrap and your rear springs will last longer with one. But you don't absolutely need one.