You can get an aquarium bubbler for around $10 and it will keep them pretty good overnight. I have a battery powered bubbler but it does not put out anywhere near as much air as the 110 volt one, so I bought an inverter for about $15 and run the 110 volt one in my boat also, just plugged into the cigar lighter outlet.
I have one of the flow trolls but I got tired of putting it in and out of the boat and forgetting and dragging it down the lake. I use a 3.5 gallon insulated bucket now.
Mark 1:17 ...I will make you fishers of men