I have a cap on my bed and have put my bass in there several times without issue. BUT - I have the newer Fender fitted hardshell case, which is a huge amount of protection. I would never put my bass in a truck bed with just a gig bag as there is not much protection from the bumps and jars. Also, never in the winter - it always goes in the cab with me. Imo, gig bags are flimsy things for carrying your bass by hand from point A to point B. Just my own feelings. There are more robust gig bags, I know, but none offer anywhere near the protection of a fitted hardshell case. Just sharing my take on this...