You really should strongly consider replacing your tires with E rated tires. A 2500 lb camper is going to significantly overload your GVWR and while the D rated tires may be within the limit on the sidewall to support loading your truck to its GVWR, they only take 65 PSI. I think a bit of reading around here would find that nobody here would take off down the road fully loaded with only 65 PSI in their tires if the tires would take 80.
A 3/4 or 1 ton truck should only have E rated tires installed. I don't know why tire manufacturers even bother to make D rated tires in the sizes that are common for 3/4 and 1 ton trucks. D rated tires are fine for a 1/2 ton hauling a pop up camper. They really don't have any place on a 3/4 or 1 ton truck.
For the record, I have a single wheel 1 ton and it's pretty unlikely that I could succeed in loading a 2500 lb camper on it, taking the gf and dogs, and loading all of my stuff in it and not overloading it (it has approximately 2800 lbs of payload remaining with a full tank of diesel). A 3/4 ton truck has 1100 lbs less capacity than a 1 ton SRW of the same year. That's not to say that the numbers on the door are everything, but keep in mind that your camper is heavy enough that you're going to be overloaded by quite a ways before you even put anything in your camper.
I don't think the lift is really a big deal unless your truck is lifted really high, so I wouldn't worry about that. The air bags will help with leveling it as well (because your back springs are going to be maxed out, especially if you don't have overloads). Tires, however, are a very big deal. The good news is that if your truck will take 16s, there are a ton of E rated 16" tires that will take ~3400 lbs IIRC.