You need to decide whether it is more important to keep you present truck and get a popup camper or get a 3/4 ton truck and a hard side camper.
The lightest hard side campers will have a dry weight of 1700-2000 lbs. and to that you will need to add 500 lbs. for gear, water, foot, propane, etc, and the tongue weight of the trailer. That adds up to needing a truck with a 3,000 lb. payload capacity which is easiest to find in a used 1-ton truck. Get a SRW with a gas V-8 and 4.10 gears and you will be able to haul most campers. A popup camper is going to weigh 1000 lbs. less and this also translates into a more nimble RV on bad roads and trails.
A 1/2 ton can be modified to handle that payload but it is not going to be cheap to do so, though it may be worth considering. Adding leaf springs, axle truss, heavy duty shocks, rear anti-sway bar, new rims and tires, while expensive is going to be cheaper than buying another truck.
If you weigh a truck at a local CAT scale you will get the weight at the front and rear axles. With the rear axle weight known, you can subtract it from the total load capacity of the two rear tires and have a good ballpark number for the heaviest load you can put in the bed of the truck.