I went with silicon sealant. Guess what? It works great. So great I can pick up the empty freezer by the collar and have it hang. Why did I try this? My damn collar was about 1/6" too small- must've shifted while gluing it together and the lid didn't close all the way.
I started on a new collar this evening using some much higher quality wood this time. I went with 2x6 instead of 2x4 as most of that wood is trash from home depot.
Note to collar builders- drill your tap shank holes before applying stain and polyurethane; it is a lot easier and will save you touch up time.
Time for a beer