I still don't understand how your ordinary average Josephine in a C172 (or a Technam) is going to have any idea where these unknown, isolated strips are even if she hears the call.
I think we need to see more of the supposedly busy ones on the charts, so,we all know they are there. Then they can all have 126.7 or preferably a discrete frequency. The rest obviously have so little going on they don't need more than see and avoid, anyway.
There is a difference between the needs of those "flying in" and those flying past and this difference doesn't get much consideration in most of the discussions.
Re SAR with a mate...How many of the Unknown, isolated airstrips have phone coverage on the ground?
Kaz