The best thing you could do is throw one of these babies or something similar into a cooler.
Second choice is something like this ...
I have one of the second doo-dads I will gladly lend you for the tourney. I'll take a look it tonight, I believe it takes 2 AA batteries. If you go this route, I would strongly recommend you change the water (with you bail bucket) a couple of time throughout the day. The water temperature shouldn't be a big deal given how early in the season it is. My biggest worry with just running a bubble aerator would be the fish "excrement". Very toxic - hence changing the water.
BTW, and while I know catfish are super hardy fish, but I had 4 (total weight of 18lbs) at the catfest 2 years ago in a cooler. Just changing the water frequently on that day was enough to keep them peppy.
Oh, and RJ, if you think that this will be your one and only tourney, you're crazy.

They get pretty addictive. Might be time to consider turning some of that storage into a fish friendly livewell, cause you're gonna rope yourself into another tourney some day I'm sure.
See you next Saturday.
M.T. Livewell