IO540, drive from Elmas to Fenosu is not more than one hour on a motorway - like road.
Donīt know about Avgas in Oristano, however it would make me wonder, if they donīt have it at all - as most of the local aircraft will certainly need it! However, as usually in Italy, the fuel is owned and distributed by the local flying clubs, for use in their machines. There might be limitations in giving that fuel away.
BTW - there is also some scheduled traffic into Oristano:
A couple of months ago Denim Air from Holland started scheduled services with Fokker 50s to FCO and - I think - Pisa. Heard them often on the frequency, donīt know the current situation.
FA10