I can turn a wrench

A few questions on this. Did you bleed the air out of the cooling system after replacing any and all of the parts? If their is air trapped in the cooling system that could cause an issue with the circulation of coolant. Do you heat hot air out of the heater? If you do not get hot air out of the heater after the vehicle has warmed up that indicates little to no circulation. If you have bleed the air out and get hot air from the heater I would try another thermostat, because you may have gotten a bad one that is not opening or may have a water pump that has gone out or a clog somewhere in the cooling system.

Usually a vehicle with a tow package has a larger radiator, oil cooler, transmission cooler and some times beefed up suspension parts (shocks struts springs etc.)