A good idea! 
never thought of that myself,
maybe the Southern 100 supporters club? https://www.facebook.com/S100SupportersC...cale=en_GB
Friends of the TT riders association https://ttra.co.uk/fottra-index.htm
The Dan Kneen Charitable fund https://torq.im/
some that may fit the bill 
& Joey Dunlop Foundation, of course! https://www.joeydunlopfoundation.com/

hope that helps.
maybe I'll look into it too!