I have a funny feeling that renting out fleets of beater dirt bikes to the folks who would rent beater dirt bikes as a group would end in tears ... either lost or wrecked bikes, or massive liabilities.
When I was last on the Isle of Man, I went by the only bike dealer on the island, Tommy Leonard Honda. Turns out that he used to rent bikes once upon a time ... you'd THINK that it would be a good market for that, since it's difficult and expensive to get your own bike, or a English rental, onto the bike-mad island.
He started with larger bikes, then just did 125s, then quit. The customers wrecked or abandoned ALL of the bikes, and it was a losing proposition.
I'm sure that some folks do OK renting bikes here, big cruisers for Europeans to ride Route 66 and such as that, but I can't imagine light dirt bikes making it back very often ... !!
Lannis