Yes so who articulates the position clearly and authentically? The position you articulated above seems reasonable but I wouldn’t call it SP- Francis is still materially Pope( insofar as we recognize his material occupancy of the chair and resist him, the position could still be classed as a variant of R&R- albeit not “classical R&R” as you put it)
Here's one example. +Sanborn persists in his dogmatism regarding not putting
una cuм in the Canon. But if someone is materially Pope-designate, it would not necessarily be inappropriate to insert his name in the Canon with the
una cuм. So for him the material occupancy is meaningless, whereas the classic SP would be very similar to what Father Chazal articulated in terms of the implications of the material occupation, that the Pope (or Pope-designate) remains the visible sign of unity for the Church. He's also backed away from the notion that the current Cardinals could legitimately elect a pope or that Bergoglio could convert and resume the papacy. So it you take those implications out of the mix, the distinction between SV and SP become meaningless.
Part of the SP mentality has to do with the notion that only the Church has the authority to handle the matter with any degree of finality, and that stance is largely incompatible with dogmatic sedevacantism. SP is by its nature a much more moderate variant of sedevacantism, and it actually addresses many of the R&R objections against sedevacantism proper.