During my search for more info about the Ski/Caterpillar system that Goldie found, I bookmarked some other little gems like this one:
This is a page from an accessory book from 1964 showing really cool stuff for a Honda C105. Perhaps we have it for you! ;) Quite likely, you cannot find this stuff anywhere any more. Too bad, because it would be pretty neat to have it!
Source: Cub Ki-Mono