Thanks for the help! Those other designs are nice, and the seatpost hitch is so tempting, just for simplicity's sake. But I feel that they look somewhat more lumbering and less stylish, so I need to have the hitch lower down, unfortunately. I am currently entertaining the idea of buying my own welding gear, there's some stuff quite cheap around here. Probably for about as much as it would cost me to have someone weld two of these trailers together I could buy my own equipment.