I'm modeling a "tall" HT8 enclosure at the recommended .655 cu ft. volume to fit in my HT speaker column design. The flat packs come with 1/2 inch Baltic birch - I'm wondering if 1/2 inch mdf is sufficient with a single window brace or should I spring for some Baltic birch? They'll be hidden, so no fancy finishes needed. Also, since small batches of denim is impossible to find atm, will a 1.5" Walmart foam topper work as a cabinet liner? Should I follow the HTM-8 guidelines to install? Thanks!