When you tow it,another thing that helps is to go into your turns gradually;suddenly deciding to turn will leave the towed rig unable to get its steering reaction initiated before you turn. Just steer into the turn kinda slowly,and straighten out kinda slowly too. Takes a little planning on your part,but makes the trip a lot less thrilling too. If you feel a little weight will help keep things moving the right way,try laying a couple of sandbags over the front crossmember and strapping them down with tie-down straps.
Speed