The wifey found a low 30”x60” hardwood table for $50 at a local consignment and furniture place. 18 baseplates (10”x 10”) and a tube of Liquid Nails later, the “land” and “water” were secured. Today I finally had a chance to add some Dollar Tree bins to the sides with wood screws and they’re surprisingly sturdy. And with tighter gaps than piston rings coming out of an Alfa factory!
Note: Baseplates were under $5 each, less than half LEGO prices, but in many ways better — fully stackable if you wanted to go that route. Brand is called Brickyard.