I "solved" the issue by having a 5/16" threaded brass insert installed in my instrument, which opens up the use of the NS Design accessories on an Ergo. I had become used to the shoulder strap system from my NS Design cello that I owned previous to the Ergo, and wanted to continue using it. I found the NS Design shoulder strap, tripod, and endpin to be stable.
I found when playing my NS Design cello with a tripod for a while, that it was difficult to get used to not balancing the instrument against the body, regardless of whether it was "stable" in the sense of staying put while I played it.
Jesse did this for me at build time. It likely could be added to an instrument after the fact, by Jesse or by someone else who's not afraid to drill the wood and install an insert. I wouldn't be afraid to use a bit of polyurethane glue to strengthen the outer thread's hold on the wood. Of course if done incompetently it could be a risk.
None of this is at all to detract from the "native" form of an Ergo instrument--simply recognizing that not everyone prefers the same things.