If you can make the ground poles, logs, the bridge, etc, part of his daily routine. Put the ground poles where he has to walk over them to get to his paddock or to his grain bucket or in and out of the barn, same with a log and the bridge. Make walking past a trailer a "normal" thing too, then eventually open the ramp and walk past it, eventaully try to get him on it. Best to have it hooked to a truck the entire time or at least park a truck so it looks like it is and hook it when you try to load.