This is a recent AliExpress item so still to be tested. Length is unsure.
Looks like the Elevate or the Cabratec board.
Minimum order quantity : 10 pieces + 700 USD shipping = 250usd per board + taxes.
[Yes, the first picture is a Fliteboard picture)
Then you have to build a waterproof box to insert in the middle of the board and strong enough to bear the foil attached to it.
@tylerclark, would you show us picts of your electrical box, alone, closed and open ?