Can all 5th wheels double tow?

Double towing is regulated by the states and they almost all have different requirements. Here in Wyoming, as long as all trailers have brakes, we can double tow with an overall length of up to 75', I believe. When we bought our Jayco Eagle HT 26.5 RLS, we went to a professional welder who proceeded to reinforce the I beam frame almost to the back axle and then fabricated the hitch from the ground up, taking almost five hours, including putting in a plug for the boat trailer. Boat weighs around 3,500 pounds when ready for fishing and towing and, so far, we haven't had any problems. We have been towing for 25 years, first with a Jayco 21.5 SD which towed boats weighing as little as 2,000 pounds on the trailer and as much as 5,000 on the trailer and measuring around 73 feet at a maximum. My HT back then didn't come with the a hitch with a 300# weight capacity. By the way, my hitch is welded to the bumper, but I believe that is only because the welder wanted the hitch snug to the bumper, I would never use a bumper hitch to tow anything.