P tires on a truck are required by fed regs for its capacity to be derated by roughly 10 percent. A P tire with 2300 lbs of capacity then has only 2070 lbs. Most 1/2 ton trucks rear axle (3800-4000 RAWR) may weigh 2500 lbs fully loaded which leaves 1300 - 1500 lbs for a payload. Actual numbers depend on actual scaled separate axle weights.
I'm not of the opinion you can never have too much truck.
Brakes ?? Brakes are vastly improved on our 1/2 ton trucks from the days when 15" wheel and tires were used. IMO simply a non issue with the new trucks.
I do think the proper truck with the proper rear axle is needed as its gonna' carry all of a TC's weight and needs to be addressed for a dedicated truck carrying a heavy camper.
And in particular its the old story of 2500-2800 lbs siting on a small semi float rear axle full time. These axles are tough but with just one small bearing on the axle ends their not going to have a normal life expectancy as the full floating axles on the 3/4 or one ton trucks.
I've towed/carried weight well over GVWR and GCWR but I won't use a 1/2 ton or 3/4 ton truck with a semi float axle full time above its rating.
The F150 HD with the HD package at 8200 GVWR and a 4800 RAWR is the only 1/2 ton truck that won't be over the trucks RAWR ratings. The GM simply doesn't have enough axle for a 2500 lb payload.
Oh sure the tires/wheels and more suspension help can be added but it doesn't address a semi float axle that is rated at 4000 lbs and is carrying 4500-5000 lbs.