I agree with shortbusgeek!
I have also done tone of research on trailers and the two kinds that I like the most are the two horse straight haul or 4/6 horse straight hauls. My horse simply does not load into stock trailers. They are too small and he doesn't like the open-ness of all the windows blowing wind into his face. He will load in backwards facing slant trailers, like the Turnbow (Slant load reverse slant options - Turnbow Trailers - aluminum horse trailers, aluminum horse trailer, custom trailers, custom trailer, horse trailer repairs, horse trailer repair, living quarters trailers, living quarters trailer, horse trailer part) which I also like because the horse never has to back up.
People also don't realize how imperative it is to get a goose-neck if you can!!! I watched my horse come flying off the road in a trailer into a snow filled ditch and the only reason that trailer didn't flip was because of the goose neck, and even then the entire rig almost flipped for an instant. Had my horse been in a bumper haul at that moment, he wouldn't be alive right now, I'm sure of it. He came out of that goose neck 4 horse straight haul head to head (it sounds a lot like shortbusgeek's trailer) in his shipping boots without a scratch.