That bracket is an outrigger that supports the wall. You should be able to buy a new one from Lippert using the frame number usually found near the tongue. Failing that, reshaping the old one will result in a weaker piece, so you could fabricate one or reinforce the straightened one.
It looks like that bolt held the floor and should be repaired. That would be a major project. Check with your insurance and tire manufacturer to see if you can be compensated.
I agree that a steel liner would be a benefit but there are several pitfalls. Water will get behind the steel and cause rot problems above it. If there is much room, it could be spaced away from the floor so it can dry. The edges, and especially the ends, would need to be anchored so that a failing tire cannot grab it and cause even bigger problems.
Galvanized steel is available and that should last longer than the poorly painted frame.