I carry a Tempo 12 gallon on the port side and usually carry a 52 quart igloo cooler next to it under the motor well. If I leave the cooler out in the cockpit another Tempo 12 will fit under the motor well. But if I don't want the cooler out in the open and put it under the motor well, then I also carry a Honda 6 gallon in the motor well. I would just love to tear out those hull liners and put in the saddle tanks like those shown on this forum. Wish I was that handy. That would solve all the problems with space for fuel. If you get bigger Tempo tanks make sure to get the low profile caps, otherwise they won't work. For most of my boating on the Columbia, in the San Juans, and offshore from Newport I have found 18 gallons to be more than adequate. But next summer I am planning a trip up the inside to the Broughtons and will probably take both 12's.