3/4 inch hitch receiver mounted on the Rex...
Small sport trailer from U-haul...
Duct tape the kid in the trailer and go to town on the Tail
Seriously, there are some wristbands out there with plastic balls in them that press on pressure points...there are some anti-seasickness ones. Ask yer friendly doctor, unless he's anti-holistic, in which case, ask your local acupuncturist.