Aside: is bryopsis itself harmful to SPS? Aside from totally messing up nutrient levels and invading substrate? I see that a large fraction of folks voted that it's beautiful and can be left to be...I think that is a fair number -- anecdotally of course. I've been following this thread for a long long time and that feels about right.
When it goes bad, it can go bad very quickly. Other times it can cause a slower decline I've never been able to understand when/why, but I have seen it first hand and it isn't pretty. That is why I never recommend it for just simple GHA. For bryopsis though, you really don't have another alternative other than removing rock.
If you have a buddy with a nice stable stick system, maybe park some pieces until you are clear? If you see things turn bad, be rerady to do the usual WC and carbon, but also be sure to SHUT OFF THE LIGHTS. Maybe watch ALK as well.