Ok peeps, here is a suggestion for your consideration:

Only Captains sit reserve.

The company would have to enlarge the pool of Captains to cover the increased flying in their category, but would require no more pilots overall. And they might actually need a couple fewer because one pilot could cover both seats.

As all FOs would be line holders the newhire involuntarily sitting reserve, (whether for a few short months, or several long years) would no longer be a thing. Likewise, when furloughs happen again, the bottom guy will not feel like Prometheus getting his liver ripped out day after day for eternity. Being the junior reserve pilot would actually be a choice. And would be fairly compensated, enjoying a healthy pay bump over peers who choose to remain FOs and enjoy the perks of seniority.