I highly suggest this solution for the bottom of the SS Platinum grills. It isn't very hard to do at all and bottom line is that it retains the rust free qualities that make the frame so great. The biggest hurdle is sourcing the aluminum sheeting but I would think a lot of metal supply outfits will have something that works and it shouldn't be all that expensive. The other issue would be the front and back cross members. But those could be added in with the tube connecting nuts. I just finished riveting this panel in a little while ago.
The other side is the shiny side. I keep the brushed side up because it more closely matches the stainless steel. Also, you can see how much it shows finger prints and stuff.