I think this is fairly common, that DEF usage is fairly high at the beginning, but will start to level out as it's driven more.
I didn't receive a full DEF tank when I purchased mine, and I had to refill mine around 4,000 miles I think.
I pulled my Keystone Zeppelin 19' (about 2500 lbs as nothing was loaded up in it) for 1h45m from Worcester to Pittsfield along I-90, set cruise control at 65 mph, and averaged about 13 mpg.
I ended up returning my air bags, as I didn't want to deal with the hassle of maintenance, installing etc. Installed the sumosprings, mine touch once my TT is loaded up. Definitely was a better ride.
I went from 255/75 MTs to 315/70 ATs and my mileage has stayed about the same, roughly 25 mpg. I drive anywhere from 68 - 72 mph, most of my miles are highway.
Did you calibrate your speedometer? 19-20 honestly seems a bit low if you're doing mostly highway.
I don't usually keep track of it, but I've seen it go up to 235 when I was towing a 6000# wood chipper. But highest speed was around 55 anyways, since I didn't take any major highways.
If the payload of a 1989 Comanche Metric Ton is a 2200 lbs, I think you would have been fine... ;) (yes I know, coils vs leafs)
In all seriousness, it looks good! It's almost worth the reaction I'm sure you got from the dude loading it up.
Dropped mine off today, confirmed that it's a leaking seal. They said they show an axle assembly in the warehouse, hoping to know if they'll be able to get it tomorrow or not.
Interesting. I ended up buying both, was going to decide what to do later. I'll probably install the SumoSprings first, see how it goes, then maybe the air bags if I don't like how it feels.
I picked this one up when they had a combo deal for a free battery and charger, works fine! Some of the Milwaukee stuff is a bit too expensive for my taste/use.
https://www.lowes.com/pd/CRAFTSMAN-20-Volt-Max-3-8-in-Drive-Cordless-Ratchet-Wrench/1003014338
Not sure if anyone else has done this, but I added two washers on each side to the steering stop bolt in order to stop rubbing on my stock rims + 315/70R17 BFG KO2s. Yeah, you lose a little turning radius... but let's be honest, it wasn't that great to begin with, lol