Even a double hole.. if it fits a boot it's deadly. They may not freeze over for more than a day, depending on temps. Rob almost broke his leg in one last year stepping out of Lloyd's van and we had, I believe, Dave stepping in one first thing in the morning to start off wet the day of Fishing for Tyler a few years back. Lucky he didn't break his leg/hip.
If you need to do them that way bring a branch to stick in it as you leave.