Thanks everyone. I think Pop Bob the trucker is right, and I'm also going to install some square u-bolts on the front of the bed to add one additional ratchet strap around the frame.
To Joe Colman, it's not that I'm uncomfortable towing with the tailgate down, it's that without the tailgate up and latched, it would hit the tongue jack on the trailer, and even without a tongue jack, the turning radius, without jamming the tailgate into the front of the trailer, would be next to nothing. I do use ratchet straps pulling forward and back on both sides, and with this 3rd one across the front, I'm thinking I will be good. Thanks again for all the great input.
Kevin