its worth the extra to go up to Kirkwall for a visit and if you haven't been to the Orkney's before worth maybe a day or two on the bus seeing the local sites.
Orkney - Scotland | VisitScotland
Going for a whaz round the island airfields is worth it as well.
If you get in touch with the tower at Kirkwall they were in the past very good at getting a weekend pass including parking for the islands sorted out.