Ah. This is a feature that the front side of the gaucho sits on, the dinette seats sit on a similar "shelf". I don't think you need to add anything. As far as I know, the gaucho adds little to the structure to a
Trillium. That said, some Trillliums suffer from a sag of the front curb side corner. The gaucho may help hold it up, but since there are frequently two doors in the front of the gaucho, I don't see it providing much support.
What do you plan to put there?