I pulled my tanks out about 5 years ago when I purchased this boat. Inspected and found that where they sit on the bottom rubber strips, was where most of the corrosion damage was. However, was not too deep, or not deep enough to be concerned for new tanks. So I cleaned them, sanded, cleaned again, used Marine Tex epoxy over the corrosion spots and then coated tanks with Coal Tar Epoxy as recommended by many as protection for fuel tanks for the long term. At same time, replaced all fuel lines, even though the originals looked to be in great shape after approx. 19 years. Hope the new rubber holds up as well.
To cushion the bottom, did not reuse the rubber strips, but instead added 1/4" PVC strips adheared to bottom using 5200 before coating with the Coal Tar. I think I am in good shape now long and have more peace of mind. By the way, this method follows the Dale Pescoe Marine Surveyor method of protecting aluminum tanks.