If less than an hour trip, water temps are less than 60 degrees and you keep the density to about 1 10"-12" trout per 2 gallons of water I have gotten away with using plastic storage tubs and using a 12 volt to 120 volt power converter powering a high quality air stone. It isn't perfect but it gets the job done. I used to use that method when stocking trout into our creek. I didn't want a big stocking truck announcing to every local free trout to come poach. The farm I buy trout from now loans out transport tanks free of charge so I use them.