I have a pop-up camper (with almost all options) whose data plate reads 740 lbs. From reading here, I knew the truck wouldn't handle the camper in stock form. Here's everything I've done:
1) re-geared my Taco to 4.88
2) added beefier leaf springs (Alcan)
3) added beffier shocks (Bilstein 5100s)
4) added Firestone air bags
5) installed E-rated sidewall tires
My truck now rides great, corners great at speed on the highway and I have plenty of power for real mountain driving both on and off road.
Depending on how your camper is attached to the truck, you might not NEED to install the Demello frame stiffeners although they certainly will improve handling. I am considering installing a flatbed on my Taco and having 4WC complete my camper with some storage boxes. If I do that, I will probably have the frame stiffeners installed.
Although your truck is rated to accept the load, its performance limitations will become apparent quickly in terms of engine, braking and handling performance. If I were to propose a modification sequence, I'd go 1) E-rated sidewalls tires, 2) air bags, 3) re-gear and 4) springs.
A coupla questions to ask....
1) What is the terrain like that you anticipate driving? Mountains or rolling plains?
2) Does the truck also serve as a DD?
3) Do you pack the kitchen sink when you camp or do you cut down your toothbrush to save ounces in a backpack?
HTH. Best of luck!