I still don't see how boarding C+ before Sky is going to help you here. Since you're PM, boarding Sky before C+ would be more to your advantage, since that would exclude some non-sky people who purchased C+ directly.
I don’t see where boarding SKY before C+ is an option. ? With C+ you get SP boarding, so paid or unpaid, C+ pax are in the same SKY boarding lane with PM. I only fly C+ on shorter flights which almost always are on smaller planes, so my C+ flights usually have no more than 3 C+ rows and I’d venture to guess that besides me and my companion, some of the others are DM/PM also, so really not so many paid non-sky C+ pax there. But my routes are medallion-heavy and the SKY boarding lane is usually a zoo. Once in a while I fly a route with relatively few medallion pax where SKY is enough to assure my bag will not end up in a bin several rows behind me. Seems like such a petty kvetch, but really, C+ is such a joke of an upgrade, at least it would be nice if the bins really were “dedicated.” Then I wouldn’t care when I board or with whom. Last would be just fine.