I propose we properly document the use of golf=out_of_bounds on the wiki. I propose we suggest using it on ways as that is what is marked in the real world with white markings/sticks. Proposal:Golf=out of bounds - OpenStreetMap Wiki Please discuss this proposal on its Wiki Talk page.
You should make it clear you are proposing a new type= to relate it. This should not be done lightly. Data types needs to be minimized, and scrutinized. Why don’t you start with type=site + golf=out_of_bounds ?
There’s type=circuit for sporting. Unfortunately it’s for racing only.
Cf route=golf question. It’s very awkward as a “route”, but you could use a route=golf for each =hole , and a superroute=golf for the entire course. Then you can relate the =hole and =out_of_bounds in each =hole uniquely. If needed. Talk:Tag:leisure=golf course - OpenStreetMap Wiki
Please drop your feedback into the discussion page on the wiki so that everyone can see it regardless from where they get the information per the RFC process described on the wiki.
As you have noted there is parallel work on the overarching leasure=golf_course. I agree with you that it would be better to solve that first and then circle back to this to not create to many relations.
The proposal have been moved into voting, please vote!