Land cruisers have a very overbuilt frame. Your friends have probably seen too many jeeps and fords in their shops. I don't think theres any amont of suspension cycling that will damage a toyota frame.
There is a video out there somewhere of me knocking over a dead tree for firewood with the mini truck in my avatar. Frame was fine, 80's vintage smittybilt tube bumper was not. Nothing a tow strap, an apple tree and reverse gear couldn't fix
:edit: come to think of it, I also tugged a bunch of 4" fence posts out of concrete with that truck too. No damage that I could see/feel 
There is a video out there somewhere of me knocking over a dead tree for firewood with the mini truck in my avatar. Frame was fine, 80's vintage smittybilt tube bumper was not. Nothing a tow strap, an apple tree and reverse gear couldn't fix

