I have a 2021 321BH that I am wanting to install a slide out topper on. I am looking at the Solera brand. The unit is in storage right now and it will be a while before I can get to it. Question is, does the gutter rail under the slide out support the awning (slide the end of the awning in the channel)? Or do you have to install the awning bracket bar 3in above the top of the slide out? Thanks.