Might be fun, an enduro/Turtle Scramble? I don't know modern venues but one would have to propose a special class, like "air-cooled" or "plated duel sport" for any serious event and be run far enough, long enough for TW endurance to factor in. A Just-for-fun race like the 24 hrs of Lemons for beater cars could be done for tw's, pit bikes,etc to weed out competition based machines and not be taken too seriously.
I recall reading some years ago of someone building a Dakar entry based on a TW. Don't know what class he raced, or even qualified, but probably was