Clean work Aaron. Just a few points to add
The required air gap on a t&p line is 2 times the pipe size per code. (UPC) This would be in the "Indirect Waste" section of the code book.
I have another suggestion, if I was to install the water heater, I would have not installed it on the pvc couplings, this makes the water heater unstable, unless you install it on a water heater stand, which in your case is not needed. The water heater has a bottom to it, the 2" you raised it will not do any good. I see what you were trying to do, but it isn't necessary.
I also would have moved the water heater closer to a wall, not floating. I am not sure of your set up, but I am sure you could have positioned the heater against a wall, just worked the water lines over, instead of straight down to the unit.
The tee is very dangerous as the copper fittings are not directional fittings, unless a 90 is used, that tee has to go. It would be illegal for the HVAC guy's to tie in their condensate to your tee.
Great Job Aaron, you are getting there!! I like the way you post the pics and remember, we are only here to save you time and help you learn the right way. Congrats on the new van buddy!!