Bent a hub? On an F-150? Come on man, those hubs are built like tanks. I've hammered lugs on with an impact for 15 years on everything from Civics to half tons and never bent a hub. Cracked rotors happen from heat and cheap metal, not from over torquing. Torque sticks are fine if you want them but acting like everyone who uses an impact is out here destroying their truck is a stretch. Sounds more like that hub was already on its way out.

That 40 degree drop at the boot clamp is a solid tell. I've been doing the same thing for about a year now, but I check both sides of the clamp, not just one spot. Last month I found a 25 degree difference on the cold side pipe about 3 inches from the coupler, which turned out to be a pinhole in the pipe itself, not the boot. What made you think the clamp was the issue versus the boot itself just being old and cracked? Also, was that 40 degree reading taken right after a hard pull or did you let it idle for a bit first?