SLUG control/cabbage growing in Zone 4

Could be worse - only a real problem on cabbages - didn't see any solution in archive, though I did try coffee grounds and eggshells ... maybe helped a little.
Do they leave the plant and return to the soil during the day? Can I closely wrap my plant with row cover if they aren't hiding in the lower leaves? Have already removed lowest/ground-touching leaves.
Finding only tiny ones in the morning and wondering if they stay in the leaf crotches during the day.
Thinking about placing pieces of cardboard to "catch" them overnite. Not very many cabbages left - trying to know for the future.
Kinda funny - no slugs on red cabbage container-grown off ground, but plenty green cabbage worms ... none of those in 30-gal grow bags of green cabbage, but there are the slugs!
Wondering if I should, next year, put all cabbages together in small bags on my "table" and cover them with row cover.
I guess it wouldn't be bad as a "mono-crop" situation as long as they were covered.
Thanks ALL - happy harvesting!

I've used beer (or brewers yeast in water) with a little detergent to break the surface tension in shallow bowls to attract slugs. Messy to deal with.

Now I've got ducks, so collecting the slugs in the late evening into a sealed bin with air holes and greens that are duck compatible (like dandelion) is stacking functions as the ducks get special breakfast! Headlamps work well for this chore. Less messy to deal with.

Rock piles to attract garden snakes can help, but they didn't solve the problem this spring without me intervening as well due to the weather. Not messy at all, but they couldn't keep up this spring.