I've also got some paints that mix to virtually the same color as the mat . . . so that will work fine. And I've pretty much decided upon Pre-Dread bases of 30mm x 100mm (roughly 1 1/4" x 4") because I do want some sea room between ships.
I've located some pre-painted (white) flat wood "door stops" at our local Home Depot. They are fairly thick (9.5mm or 3/8"), but that's fine since I want to see the ships handled by the bases and not the vessels themselves. Furthermore my plan is to put the ship identification on the sides of the bases; not on the upper surface.
Finally I just ordered another mess of ships from Panzerschiffe . . . 18 cruisers (a mix of Armoured and Protected Cruisers for each side) and 9 merchant ships (set #5) for convoy and commerce raiding use.