I have only been through it once now, and what I did was observe my snake carefully to judge his interest in food.

on feeding day he is normally alert and watching for food. during shed on feeding day he was coiled in his hide and not displaying normal feeding day body language. I skipped the feed but a couple days later he did start to act like he wanted a feed...so at that point I offered and he took it.

I would think that every snake is different. I would also say that skipping a feed during shed probably has no downside, but feeding cautiously with non-live prey is probably just fine too, as long as you are ready to throw away a refused meal.