Here is a company that rents out Triumphs for self-guided tours:
http://www.triumphbiketours.com/
I did this last year... my wife and I took the Peloponnese tour. They provided us with a day-by-day itinerary, and pre-booked all of our lodging. You may be able to negotiate just the rental of the bikes, providing you give them a fairly detailed plan for the trip. Just a thought so that the folks that can't get their own bikes there will have an option. They do have Sprints (or at least they did last year).
