Port-a-Canoe dolly... that breaks down and uses the sling as a carrier for the parts.The hole in the top of the pockets for the snugger straps allows water to exit the pockets when packed up.The axle could be broken down lengthwise with threaded inserts as backing plates and stored in the pockets or used as a handle as shown with a hole cut (and binding tape around it)in the sling..or just the center portion.The wheel axles could just be bolts with no axle across but I'd be afraid the wheels might catch on some rough ground and not roll true..therefore the axle across.Quick release pins or wingnuts..with washers hold the wheels on for quick disassembly into the canoe.
The sides only really need to be slightly higher than the wheels(6"?) so the wheels can't rub on the canoe and the snugger straps have more tension to the gunnels,tightening the canoe in the sling.
The sling/packer could be made with all that 1.9 oz nylon you've got lying around.
A couple easily made aluminum gunnel clamps on strapping with snubbers hooks it to the boat.The flex of the axle shaft flexes the dolly against the canoe sides for a snugger fit and less movement.Household copper pipe foam insulation could be placed over the axle center to protect the boat..or over the top bars and eliminate the sling(if you don't feel like sewing/making the sling).
Dolly sides are 3/4-1" aluminum conduit or the equivalent and the axle holder plates 1/4" aluminum(bolted to slotted conduit).The overall length could be 18-24"whatever holds the wheels in the pocket when packed..or one wheel/bracket in each side pocket for a shorter length but wider pack in the canoe/car.The entire rig might probably weigh 3lbs + the weight of the wheels.
..or at least that's what it looks like in
my head.
The views and opinions expressed by this person are his own and not the general consensus of others on this website.Realityguy
..then I turned up the volume.. 
