math aside...but actual experience to share.
had a 2004 silerado 1500 with the extended cab..327v8 and 4 speed auto.
TT is a 1996 Nash heavey metal rig...25ft long
with no mods to the pickup, but with load level bars on the hitch, the truck sat nice and level and we pulled as well up hills as any of the motorhomes running 454 and V10s...ie...climbing a tough hill, we'd be roaring in 2nd gear and dropping down into the 35mph huff n puff climb.
but in fairness, it was a reasonable pull.
with a full water tank (under the bed in the nost of the camper), a 200lb honda trail bike in the truck bed,15 spare gals of fuel, all of our other outdoor fun gear for a week, etc... I considered us as "full" but the truck did just fine.
making the move to a 3500 duramx...oh my goodness...but the price of those is painful... I'd not hesitate to pull with a 1500 again.