I don't think many Sedevacantists act as if we're living in an interregnum (time between popes). If they did, they would certainly want to fill that horrible void in the Church hierarchy.
That doesn't necessarily follow. Most SVs refuse to be conclavists due to the lack of universal consensus that would be required to fill the vacancy; otherwise you have absurdities like Pope Bawden.
But they aren't trying very hard to get a consensus either. How many have given the project even a few minutes of thought? How many gave more than 10 minutes thought to which Bishops should/must be invited, or where they live? Who maintains lists of the Pius XII bishops? Etc.
Have they written to ANY bishops or priests, or done anything at all get get us even 1 baby step closer to a conclave to get us a Pope? Or do they believe the Papacy is optional or not necessary for the Catholic Church? Or do they deep-down believe that Pope Francis is Pope?
In the practical order/materially (which is all that I'm concerned with), R&R and non-conclavist sedevacantists are doing about the same thing. They are both "hedging their bets" or whatever you want to call it.
The only difference is, the R&R's have a picture of the Pope in the vestibule, whereas the sedevacantists have a dark rectangle where the picture of the Pope used to be (that part of the paint was shaded by the picture for years, so the paint is darker) -- but nothing put in its place. Both sides go on about their Traditional Catholic lives, and both act as if the current Pope "sorta" has the Papacy, at least enough to prevent another from replacing him.
Of the two, I think R&R is more Catholic, because then I'm not positively deposing a pope -- something only a future council of the Church can do.
And I'm just going with the DEFAULT SETTING for a Catholic. After all, the choice between sedevacantism and its opposite is NOT a Y-turn in the road, where everyone has to pick a direction. No, the choice is more of a straight road, with sedevacantism being a hard right-turn off the main road.
It takes a positive action. If you do nothing, you stay on the straight road. Everyone on the straight road (who passed up the right turn) didn't "make a choice" to be non-sedevacantist. They just refused the choice to turn off the road. There's a notable difference.
You don't get to choose the "Pope" or "non-Pope" variety of Catholicism when you are baptized. It's not like smoking/non-smoking in a restaurant. They aren't equal. One is fundamentally different from the other, not just its opposite.