SB
I too would route via Losinj. Went there last year, avgas 50p/litre. The island is very nice. Next time I was going to go via Split - just for a change. Losinj also has early closing, about 2pm, and last time I had to re-plan to Trieste due to a Eurocontrol slot delaying me by an hour. Bad decision since that slot nearly vanished by the original EOBT!
I haven't got quite your range
About 1100nm to zero fuel. So Split back to the UK, against the wind usually, would perhaps need 1 fuel stop. Pula back to UK is easier while still benefitting from cheap fuel.
Not many Greek airports have Customs, never mind avgas as well. I would always consult Kyp on the latest.