Northern Thailand

I think I have the Indonesian part of my big trip all planned, now it’s time to start on Thailand. We have been planning to head up to the Chiang Mai area from Bangkok via the train and are tossing around this idea of renting scooters and doing the Mae Hong Son loop. Anyone have any experience with this area? Is this a crazy idea? Apparently it’s around 640 km. We will probably have 5 days in which to do it and it will be early November so end of the rainy season? Not sure if we are being adventurous or just insane. Any advice appreciated. :)