I agree with the stability concern. A few options to conside is to weld braces from the trailer corners forward to the toung about three feet back from the front. This will reduce the amount of twist that you may experience in the toung and reduce the likelyhhod of a flip. Another brace from the center of the top rack to the same place on the tounge will add lenghtwise stability and rigidity. Reinforcing where the hitch connects to the tounge will reduce that potential of the hitch colapsing the side of the tounge permitting a roll over. Stiffer springs will reduce side to side sway. This is experience talking (six boats on a wider trailer built to carry boats with a lower center of gravity went on their side going around a turn in a canyon due to a combination or the turn and some braking but nothing major.) The crossbars protected the boats but I am lucky, and I am very lucky I didn't catch another car in the whole mess.