i HAVE NOT, other have
amigo, if you have the time then it is possible, some people have gone from Alaska to Patagonia (south America) on 50 cc honda cubs, so YES IT IS POSSIBLE and maybe not the best or "ideal" ride, how ever as I said, it can be done it is all about the time you have for touring.
1 thing I am consediring for my Baja tour on my scooter is gas, my Honda can only old 1.6 gallons and that translate to like 100-120 miles so aditional gas is mandatory, I am not an expert on the states you listed but I would advice on the extra gas, either the MSR 30 oz tanks or the plastics gas containers from walmart... and also study your route for gas stations, but here in Baja it would be a mandatory thing!
A motorcycle or scooter always turn a bad day into a great time!
KLR 650, Honda Beat scooter!!