Best way to do it, but it requires two identical setups (reels)…
Spool the first reel BACKWARDS… Spool however much Stealth you want on first… Then tie your connecting knot, and tie on your mono “backing”. Fill this first reel to capacity, or just under.
Next step – take your second setup (reel) and tie on the mono backing tag end that you just put onto your first reel. Reset your linecounter to zero on the second reel, and then spool up your backing (tightly) onto the second reel directly from the first. (Either have someone thumb the spool for resistance, or set the drag tighter… It would suck to get a backlash without even making a cast! )
When you get to your backing/steath connection, note what the linecounter reads. With identical setups (i.e. 2 Accudepth 27’s or similar, same diameter and type of lines, etc) you can now just spool up your backing using the known linecounter setting that you just figured out.
Obviously as Brad mentioned, linecounters are based on revolutions, not really feet, even though though they read in feet. But in this case, that doesn’t matter since you are using identical everything and spooling starting with an empty spool in both cases.
Works slick, and most trollers have multiple setups, so it makes sense to make them as close to identical as possible.