Bummer, the tubs intrude on the space that the sail panels need to occupy. This is where some creativity needs to be applied. It would be very difficult to form a big piece of steel into the contours needed to replicate those of the original sail. It might be much easier to work with fiberglass in this situation. You could use the original sail panels as a mold. You can apply some build-up material to the sail panel, such as panels of rigid foam board or modeling clay and sculpt them to the bulge you need. Then you cover it with release agent and make a fiberglass mold. Then, you add release agent to the mold and layer fiberglass and resin to it to form your new panels. There are a number of fiberglass how-to videos on Youtube. Once you have made your mold, you can produce as many copies as you want. Just a suggestion.