In an "old school" engine running a 180 thermostat was probalby fine, but on these new computer driven trucks, wouldnt a lower temp thermostat mess up the sensors and other computer driven components that was design for 203 thermostat? I have no proof or anything I'm just asking???
To the OP, I have a feeling that 7,700 lbs trailer is just a tad to heavy for a 1500 truck. I see you're in BC, depending where you live, your "hills" could be a mountain to us out east...
I have 27 ft around 6,000 lbs loaded trailer, and I think it feels close to the max for my truck.
If you go to the trailer towing forums, I am sure the "weight police" will say it's overweight, these guys always like to remind everyone 8,500lbs tow capacity is measured with one 150 lbs guy in the truck, not a full tank of gas, and no other gear or passengers. That 8,500 lbs, is probably more like 7,500lbs towing