Don't buy a fully loaded half ton truck. Every option adds weight, which subtracts from the payload capability. A fully loaded truck probably weighs a couple hundred pounds more than a bare bones truck, limiting your payload by that much.
At 7000 lbs trailer (around 1000 lbs tongue weight) with 2 teenage boys (at least 150 lbs each) you're at 1300 lbs. Add dog, spouse, firewood, bikes, etc in the bed of the truck and you're likely at 1800-1900 lbs. I would just get a 3/4 ton truck at that point and not worry about weight.
No sense buying an expensive new truck that isn't up to the task and regretting it ever since. I bet a brand new 2500 Ram in a lower trim package will still cost less than a Limited 1500...