I've got an all aluminum horse trailer that I've had for almost 20 years. I bought a GMC 2400 HD to pull it and that truck has done a wonderful job... but it's time to upgrade that vehicle. I'm retired and the horses are feeling their age too and the chances are becoming less and less likely that I'll ever have to take them to the vet using this trailer, but I need to have the option. I haven't had to use the trailer for at least 5 years but it's still a really nice trailer and I might only have to tow it one or two more times before the need for a trailer disappears. Thus, the question about the goose neck and the need for options. I found this hitch vendor that seems to know what they are talking about considering the 5.5' Lightning bed.I will never for the life of me understand the folks who try to 5th wheel tow with a half ton truck (not just EV's-any half ton). There is quite simply not enough payload to make it work and you will most definitely be exceeding your trucks capacities to try and tow that. I assure you you will be shocked how much additional weight goes on the pin once you start loading up the trailer.
Beyond payload-putting a giant 10K sail behind a 1/2 ton truck is asking for trouble.
If you are only going to be using this once a year-why such a large trailer (or a trailer at all)?