Looks amazing. I can say first hand that the Kelderman setups are great. I installed one under a Chev 3500 a little while ago and the kit is a beauty to work with, plus their support is great.
I can attest to wanting to get those bags in their operating range. The owner of the truck I did wanted to be about 2" above stock height, I ended up having to put a 2 7/8" spacer under the bag to get it into safe operating range. We had initially set it up with no spacer, but we were too far out of the operating range of the bag, so it was struggling to carry the weight. Getting them back into their favourable range made a huge difference for their load carrying capaicty, also made it less wallowy over bumps. Definitely a good idea to go with heavier shocks too. We're running a 2.5" reservoir shock from Fox on the back of this rig, and it sees a rear axle weight of around #12K, we went with 80/100 valving and it seems to be good.
Also, yes, Kelderman runs a Viair compressor in that box, and adding an auxillary line is not an issue at all. If you opted for the auto-leveling set up the 3gal tank it comes with has enough extra ports to plumb an accessory line for refilling tires etc. However, the compressor isn't huge, so it may struggle to air up those military tires. I ran an aux line on the set up I did (be sure to put a pressure protection valve in, so you don't lose bag pressure in event of a failure, the kit doesn't come with any). However, with how far this build is going, and the size of tires, I would suggest running an ARB twin or something beefier and dedicated as your OBA set up, with a small reservoir tank for it. You could potentially even fit it right behind the Kelderman box.
I'd definitely love to see this rig in person if you do make it over the mountains to Vancover. Looking amazing so far!