hose clamps and bungee cords. once my worn out ball joint on the front lower a arm fell out and i almost lost the front wheel. i used a bungee cord to tie the lower a arm to the top one, and it kept it in place till i got back to the truck 50km away!
If weight on your box rails is a concern buy a ford, I have a home built 8'x8' steel sled deck with headache rack and 1' beaver tail on my truck and it holds the weight just fine, two apex 162's, a grizz 700 & kodiak 450, or I also just had a 700 rhino se with full roll cage & rear seats up...