How much will my tundra tow long term?

This kinda sounds like a wifes tale to be honest. What ever its rated for is what you do / not exceed. As for degrading components faster sure the extra weight or strain has some factor but you start going into "how smooth is the road if it smooth your struts are going to last longer than if its bumpy , is it dry or raining causing different air density going into the engine an different power numbers , is the air clean or dusty" you go down a rabbit hole. Use it when you want to how you want to , perform regular pre trip inspections an service when needed.

its like a meme I've seen "keeping your car low miles for resale value later is like not banging you girl friend to keep her tight for the next guy"