Last trip, I noticed my 2012 F150 3.5 ecoboost started to heat up about 5 minutes into a hard climb. Slowed to 60mph and it went back to normal. So I'm looking at having the radiator hot tanked and ...
If you are a fairly low altitude and it's hot, you need to use the best fuel you can find octane wise. This will keep the engine at full advance and give you the best chance at keeping it cool.
I would be careful putting a bigger radiator and all of that. IMHO you will find the next weak link.