Like horton said, seat of the pants feel and physical performance of the vehicle will be your metrics.
Start by doing your best to simulate the payload you'll be hauling. Hit the home depot and buy that 10 bags of mulch you've been procrastinating about and throw that in the back of the Nav. Load up several hundred lbs of fake tongue weight in the camper as well.
Set the wd hitch and brake controller gain after loaded and take er for a pull straight up the nearest hiway into the mtns.
Metrics for the truck, does it go fast enough uphill for your liking, engine and mostly transmission temp. You need to keep the trans close to or below 200F or your bordering on cooking the trans.
Downhill can you downshift, use trailer brakes and maintain normal speed down the pass without smoking the brakes. You'll know when it's too much by the smell!
Handling, like suggested, find an empty road and do some swerving and emergency stop or 2 to get a comfort level there.
Then as long as you aren't white knuckled after the fact, I'd say it works for you.
