So dive 99/99 and go directly to the surface. Add a fixed length safety stop for margin. If you are not prepared to routinely go to the surface it is a deco dive.As far as I am concerned, a dive is not a deco dive if it does not exceed m-value. You can stop and offgas from m-value to a lower surface gf for conservatism. That greater conservatism, to me, is a safety margin and the stop is a safety stop.
If your stop length depends on tissue loadings it is a deco stop.
You are ignoring the issue the boat has. It has decided for whatever reasons it does not want deco dives being done. You are doing deco dives and trying to pretend you are not by tweaking one set of numbers to make a long NDL while actually diving another set of numbers to a lower, conventional, limit with actual deco stops.