I have done this witha kayak. Its just 1 1/2" thinwall conduit EMT and drilled with a step drill, at an angle, until it fits on the seat tube. BTW, don't stop fast on the cart will try and pass to one side and stop fast.
"If you can't have fun doing it, it ain't worth doing, or you're just doing it wrong."
River hunting in my Wilderness Systems Kayaks; Commander 120 and Ride 135
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