Dedicated TF Poster - Not a Tidal Fish Subscriber
For keeping them alive I just use a bucket and put a little bubbler I got from Wal mart in there and have kept them alive for a few days.
You can add ice before you are ready to use them and it will slow them down some also.
Never had luck with the rag method though Im sure it was my fault.
I just find the bubbler fool proof.
Loyal TF Poster - Not a Tidal Fish Subscriber
It sounds like both methods mentioned above would work well.
For the little I used eels this year, I tried to keep it easy and simple. I tossed several inexpensive freezer packs in the bottom of a small cooler. The Styrofoam ones are fine and disposable if you don't want to designate a hard sided one as your bait cooler. There are no puddles of water with melting so I didn't see a need for a drainage system. I put the eels between a couple of damp towels on top of the frozen packs.
I only used eels during the summer for Cobia. The cooler kept the freezer packs cold for most of my fishing day during the hot weather. The eels stayed healthy without any need to have them swimming in water while on the boat. The freezer packs made them lethargic and easy to handle. They quickly came alive after hooking, when tossed in the water.
For keeping eels alive for days, I tossed them in a bait cage sunk at a dock.