That would be the way. There is something called intermittency, which means that the sum of several exposures is not the same as one long one, but you don't say how accurate you need to be. Will you also need an unexposed strip to establish FB+F? There are others on the forum who can give more detailed advice.
In any case, Zones are not specific vales, but ranges of density, so that everything between ZIV and ZVI is ZV. Just hold a ruler against the slide as you push it in. If you need to be accurate in the spacing, cut measured pieces of card to size for each advance and push the slide against each one as you go. Easy to check with an empty holder.
For ultimate control, you could cut windows in a series of sheaths and make successive exposures through them, but this seems wilfully extravagant. I have heard of drilling a set of holes in one sheath, which were covered with opaque tape and exposed one at a time, but this would give spots rather than strips. It still looks like vandalism to me, but no doubt there was a good reason.