Things I need do to my truck to keep it in good towing shape

Keep the fluids fresh, keep the truck clean (inside and out), and don't install a tuner or a gizmo air filter. I like aftermarket tuners - I had many on my diesels. Just not worth it on a modern gas engine in my opinion. The junky air filters do a poor job at filtering, and don't add any power or mpg, despite what their manufacturers claim.