Thanks for the input and images guys. Having been on boats a lot, I'm a fan of RAM mounts, and will direct fix a ball mount to the dash plate (ala Marshall) with an aluminum backing plate. Power is via a USB dongle from the Battery Tender plug. Ziplocks are in the cowl space.
I like TMG low mount, as the soft dash only has plugs (no switches), and possibly there may be more room to angle the GPS for less glare. Scrapped the idea of mounting via the soft dash lower 5mm bolts and twisting the aluminum strap up the dash.. mock-up was too prone to movement, and would've been a wobble-fest. There is a way to make a big "U" mount to the lower soft dash bolts, but it'd be more of an exercise of "just to do it that way", no real improvement.