I had thought it would be okay for me to file a flight plan to fly out of and back into the restricted zone and base at another airfield for the day. It would need to be a good weather day obviously to keep to the plan. The Olympic Airspace website suggests fixed wing aircraft need a mode A/C or S transponder, but I've been hearing recently that it has to be C or S to fly in the restricted zone. Since my aircraft has a mode C transponder but is placarded "No Alt Data", I'm now not sure I can fly at all.
This might be a good excuse for a flying holiday though!