I towed a 1994 21 foot Coachman TT all over the countryside for many years. Alaska to Mexico twice, many other trips from Alaska to the lower 48. That Rv went through 4 trucks.
For a little trailer, it sure did gain weight. Solar panels, two batteries, huge Curt WDH, and then all the stuff in the truck box. Two coolers full of ice and drinks. Firewood, axes, chairs, 2nd spare rv tire, extra water, the box is stuffed full. Then add me, the wife, two dogs, fuel, DEF, and all of a sudden this "little" trailer and stuff in the box, is right up to near max. While the half ton trucks all towed this fine, including the Ecodiesel and it's great mileage, the WBD bars were tight enough that the REAR TIRES WEAR OUT FAST. It don't matter what truck either, until I moved into the 2500 Cummins, which is a whole other story.
You'll be fine with that size of trailer, and should get good mileage too. I was getting up to 16.4 mpg when running pure #2 diesel towing. Just watch your weight and you'll be fine. BTW, I used 1000 lb bars, not just for the RV, but to lift all the crap in the box. It rode fine and was level, but was hard on the rear drivers. Tire rotation is a must. Also AT tires don't last as long, I ended up using Cooper HT3 highway tread, LT E tires with good effect. I had no airbags nor needed them. Heat is another thing to watch on long grades and hot days. I would try to avoid carrying full waste tanks if possible.
It was on a trip in 2019, Alaska to Florida and back. In Arizona, I had some trash to get rid of, so we went to the local land fill. It was a weigh in/out and pay. I can't quite remember exactly, but we were within 300-400 lbs or so of the 15,750 lbs of total max weight while towing. And the truck handled this all just fine. I got my best mileage on that trip too.
Any gravel pit should let you crawl on and off their scales, or the local landfill works too, and is what I did. With some algebra, you can figure out everything. I would load that thing up, full water, fuel, bodies, hell do it right before camping, and then you'll know exactly what's going on.
Welcome, and good luck with your new RV!