You should do as well with the Nissan as you did with the Toyota, they are both well built trucks but as far as the one Toyota that rotted out I would have no idea unless you live in a mountain area with lots of snow then allot of salt on the roads or you live in a costal area and tow a boat to boat ram were you getting the truck up to its wheels in salt water than I have no idea why the chassis rotted away.
One clue as far as a trucks undercarriage is to run it threw a car wash that has a undercarriage wash system, I would do that after a bid snow and a few days after they put tons of salt down and also during the summer months when I towed a small boat. In summertime I would hose off the boat plus the bottom of my truck after I used it but also paid extra to have the car wash do there undercarriage wash as well. I think it might have paid off with my 2010 Xterra but I'll let you know in about 10 years from now.