Just mucking about I found this: http://www.stableboykit.com/main/default
Started me thinking about using a RV Toyhauler as opposed to a dedicated horse trailer. The cargo/garage capacity of many RVs runs in the 3500-4000 pound range, meaning a two horse setup is possible. It requires a minimum 12’ garage space to work.
Not being an engineer I don’t know if this would work out or not. Right off hand if the decking is strong enough and the structure is strong enough, why not? Serious question, this.
Most of these “blow away” anything but the highest end horse trailers in terms of space and human conveniences but for considerably less money.
To see some examples go to rvtrader.com and look for “toy haulers.”
G.