You can never have too much truck but you have what you have. Before we bought our TT we rented a trailer similar to what we wanted for 10 days in the Ozarks.
Renting introduced us to; 10 mpg, 250 to 300 mile travel days, 60 to 65 mph, being passed by everything on the road, wind and truck buffets plus how to pick a gas station. After a week or so you will have a far better understanding of what you need.
Renting also given you a chance to take your loaded TT across the CAT scales and see the real load on each axle. It also gives you an understanding of RVing before you spend the big bucks.
On our first cross country trip, with our own TT, we started with a conservative camping approach using KOA and other full hookup campgrounds, after a few days we were using State Parks and other electricity only campgrounds.
Take your best guess at what you need, anything else is waiting at the next Wal-Mart. Take the tools and know who to change your truck and trailer tire. It is the difference between an annoying twenty minutes and waiting for road service to find you on some country road.
Our method of camping is to park for a couple of days, sight see, then move on. We do at times camp and stay put to fish etc. but we are retired so 3 to 6 week trips are the norm.
Good luck and keep us posted.
