If this is one's position, and one is forced to decide between Rome and sedevacantism, I fail to see how one could come down on the unlikely side of sedevacantism. It would seem far more likely in my mind that I erred somewhere in misjudging Rome than the extremely unlikely scenario that God let Peter disappear for 50+ years and counting and only myself and a minute remnant of Catholics realize this.
Perhaps one flaw with sedevacantism is the assumption that the Church has always been neat, tidy, in order, and completely uniform, efficient, and effective.
My thoughts anyway...
Sedevacantism to me is a sort of theological perfectionism. Perfectionists have an overwhelming desire to complete tasks perfectly. The problem is, they get to a point where they sense a small likelihood of completing an overwhelming or extremely difficult task perfectly, so they simply don't do it out of fear and a sense of hopelessness, ignore the task, and distract themselves, procrastinating with other things.
In the theological realm, sedevacantists, in my opinion have a sort of obsessive compulsive/ false view of Church perfection. Since, in their minds, the Church is so far from this view as to be almost hopeless, they simply give up and ignore the Church (believing the current Church does not exist) and then procrastinate by writing reams of words and technical arguments trying to convince themselves that the Church does not in fact exist. It is like someone who has to write a term paper finding himself cleaning his garage. Anything to distract himself from the unpleasant reality that there IS a paper due, it will take an overwhelming amount of effort to get it done perfectly.
The cure for this is to face one's fears instead of running away. Face the current Church, stare at all of the defects, wounds, imperfections, tragedies, and scandals in the human element of Christ's mystical body and then change the inner thought process. Instead of denial, one must tell oneself that this IS reality, BUT the good news is that the Church NEVER was perfect in its human element and ALWAYS has had defects, sometimes massive. Great Saints had to rebuild the Church at different times (St. Francis, etc.), BUT they never rebuilt it to the point of absolute perfection and they never gave up.
They used all of the means Holy Mother Church has guaranteed us for our sanctification, sanctified themselves first, and then through mortification, prayer, and action, through their apostolate and the Holy Spirit, moved souls towards that same sanctification and worked together to purify the Church through the channels available.
We are not called to transform the Church into a paradise single-handedly. We are simply called to transform ourselves and then others and do our small part. Leave the endless theological arguments to the theologians. As St. Thomas a Kempis says in the Imitation it is much more valuable to love than to know and all the books in the world won't bring you closer to God than simple humility and love. Then make that love effective around you and pray for these Priests, Bishops, and Pope to be good and effective Catholics and help bring about another restoration.