The list above is missing Fourwheel Campers. Lightweight, rugged, expensive.
Really if you need/want to buy used, I think the better camper (as in: better shape) is the better deal regardless of the brand.
Used campers often come with existing (water-)damage, repair is more work than you anticipate.
The interwebs tell me the payload of your truck is around 1200-1500 lbs. That ... is not much. Also, I am not sure which campers will physically fit between the rear wheel wells. Never trust the weight stated for any given camper, and calculate realistically what additional weights need to be added.
Many popup campers can be safely loaded on many 1/2ton / 1500 series pickup trucks.
The 3/4ton idea is not bad. If in doubt, it is better to have more truck than you need.