Hard to do
Hi Greg,I have a 1991 30T, and yes the tanks are small. For the fresh water tank there is a small compartment in front of the water tank. You could add a second tank here. However, you will have to cutout the vberth decking (glued and screwed in). I know since I just finished installing a 12K A/C-Heater in this location (best place on the boat, and a must have in Texas). The waste tank is the worst!!! it's smaller that my bladder!! There is some room to expand the tank size (on top of fuel tank). However, it's a pain to get at. I would like to change mine out also. If you have a plastic tank upgrade to metal tank.Jimjim.wharton@fnc.fujitsu.com