Why not LDDU-LGKC and then to somewhere with avgas? You could perhaps rent a TB20 to get the extra range 
The problem with the small Greek islands is that they have narrow openings so you mostly need to fly to/from an airport with a wide opening to make it work, and LDDU takes care of that. But LGKC onwards might be tricky… In 2014 I managed to do Leros Kalymnos Ikaria, all sleepy places, and that worked ok but that’s unusual.
Fraport have grabbed most of the wide-opening ones.
