My 'tables are on a Billy Bags LP rack. Weighs a ton, works great.
Yep, I use a double wide Billy Bags Pro rack for all my gear, including turntable. Excellent quality workmanship. Not cheap, but you get what you pay for. However, the MDF shelving sounds like dullness incarnate under my Scout. Your mileage may vary. Perhaps the thicker chassis on the Scoutmaster is less subject to this?? I still think you'll need need a Gingko or maple platform to extract the best from your table in addition to a good rack.
IME, granite sucks. It rings and this caused HF smearing with my TT. It may sound different than MDF but both are not that good for shelves. What I did find to work well with granite was to put Stillpoints between the granite and TT. This may be a workable solution for Madfloyd. The Stillpoints almost make the shelf material irrelevant.