I've got a 5 point slow as well. I towed a loaded 14 foot cargo trailer about 2,000 kilometers last summer. Probably close to 5k lbs the first trip and about 6k the next trip. If I had to do that more than twice a year I'd buy a real truck. Its not meant to tow regularly or heavy.
Not a "V4" an Inline 4. Only Outboard boat motors, old Volvo cars, and some British Fords from the 60s' had a V4. GM will be buying a lot of those iron duke powered trucks back.
We used to call those "Big-10"(Chevy) and "Heavy Half" (GMC)
A Gas Promaster has a Dodge Caravan Minivan powertrain. It is Front Wheel Drive. The only FWD vehicle capable of hauling 12,000LBS is a 73-78 GMC Motorhome and they don't make that transmission anymore.
I pulled a 6,000Lb Travel trailer with a 7,000lb rated half ton. Couldn't pull the hills without overheating.
Not Fun. I don't do it anymore because if I did, the truck would be dead.
Listen to these guys here. They know what they are talking about. The manufacturers are selling you a load of $#!+. But hey, it's your money.