Horsepower without torque with gears is still equal to horsepower with torque without gears.
As you probably know, many Class A motorhomes weigh what your total weight is and yet are powered by the higher horsepower (three valves per cylinder) 365 HP version of the V10 gasser.
By the way, when I said earlier above what our RV setup (lighter than your total RV setup) with only the 305 V10 version would do - I didn't mean to imply that I was pushing it anywhere near the limit during those times. It has plenty of pulling performance headroom left in any situation I've ever had it in.
(See .... I told you perceived diesel pulling advantage was purely preference based. ;) )