My plan is to build a 5x14 foot trailer designed mainly for hauling two atvs and the occasional load of lumber. The trailer will have a single 3500 lb axle.

Would 4x5.4 channel work for the frame if I used 3x4.1channel for a wrap-around tongue? Crossmembers would be 3" channel on 24" centers.

If 14 feet is too long for the frame, I can shorten the length down to 12.5 feet, but would prefer to have the 14 feet so I can position the load properly.