This is one of the main reasons I did the valve placement where I did, I wanted to be able to quickly level loads, and I carry a air compressor 75% of the time in the bed of my truck (I have a bicycle manual pump as well under the seat just incase). I just eye it, but levels would be nice for sure. I looked at the gas cap area to mount but I had no idea it was that easy when I was under the truck looking up at it didn’t look like to much room up there, and from the out side didn’t look like a lot of room for gauges and air hoses. . I guess I didn’t look to hard at the gas tank cover looks simple to pull off in you pictures that defiantly would have been helpful info to have.
I was original very worried about my valve placement since it was open to shifting cargo ect. I have since put on a hard cap so I know longer carry trash / rubbish in the bed of my truck ever day so that helps. I still carry lots of gear back there and trash on occasion, it shifts around some to but so far not even 1 ding on the valves.

I’m stilling looking into doing a 2.5 inch lift up front either the 5100 adjustable or ome like yours and had a favor to ask ya. I like a little rake to the truck still, at 5 psi are you level? I feel that even at 5 psi the back is a little higher then stock I usually have about 10 in the back since I have tools / heavy top and I keep it at 10 even unloaded since I’m lazy. I don’t notice any negative effects even at 10 psi empty (bounce others talk about) but my rear is definitely a little higher. I was hoping you would air up to 10 psi and see if you have a slight rake still, I'm wondering if I need to consider a 1 inch block for the back after lift in order to keep a slight rake and lower psi when empty.

edit: p.s. nice write up as well