Preventing rust questions, help!

[Rod Run]

Any type of bare metal object stored outside is going to get surface rust, that's just part of nature.

I think when you epoxied the ground, you actually added to your problem. If it was bare cement, then the moisture would absorb into it relatively quickly. Now that it's epoxied, the water just sits there and beads up, so it has longer to sit around and cause rust under your truck. Sort of the same effect as wax on your paint