RTT Bolts

I've used several rooftop tents from several manufacturers over the past 5 years, and I have bent the mounting bolts on every single one of them. They just seem to bend from 4-wheeling, and then they won't come off. I've probably had to cut ten of them at this point. I've contacted Thule Tepui about it, and they just directed me to their parts page and told me to buy new ones. I have no interest in giving them any more money, especially for bolts that are sure to bend again. Has anyone else had this problem, and what type of bolts should I buy that are less prone to bending?

Thx