My first horse was a total dweeb to load in a 2 horse trailer (or any trailer for that matter) in the year I had him. I had my old coach do some work with him, and we finally wound up using a loop of prickly rope (like jute or something) around his bum with the ends in my leading hand to help guide him onto the trailer.

However, this horse did not have a fear issue, we was just a big jerk. We also had to always have a nose chain on him to load or he did'nt think we were serious about loading. Put the chain on, and in he goes like magic! I always kept a long cotton longe line with me just in case - the prickly role was just for the initial training, as soon as the rope went on he knew we meant business.

If I had a fear problem loader I would definitely do the feeding in the trailer thing.