I'd recommend starting with the build sheet so you know exactly where you're at as far as equipment. While waiting for the build sheet perhaps get your truck on a scale.
I would imagine you could get aftermarket auxiliary cooling, gearing can be changed as well. Or lower your TT expectations.
Good luck, take your time..and do the research before buying. You're miles ahead of the sucker that goes to the RV dealer and buys a TT based on "sure you can tow it" from the salesmen.
EDIT: also check your tires. It most likely came with P rated passenger car tires. Mine did, however they have plenty of capacity and 20" rims so the sidewalls aren't very flexy.. If you're going to push the limits LT tires would probably be a good thing.