Think I will silicone caulk the inside corner of the vertical panel and the cabinet floor panel sealing that point of connection. Then I will take White Waterproof Patch and Seal Spray  and  spray the bottom panel and up each side panel an inch or so, 

It will end up costing less than a pan I priced at $22.00. Seal spray will cost about $13,00 and will give full coverage of the floor panel, 

"Gorilla Waterproof Patch and Seal Spray is a flexible, rubberized coating that seals out water, air and moisture. The applicator nozzle has a controlled spray pattern providing a clean, even coat. Once applied, the self-leveling formula smoothly covers small gaps and cracks ensuring a watertight seal. When dried,"

With the cabinet made of MDF panels they quickly absorbs moisture. The cabinet is elevated off the floor about 3/16 of an inch giving ventilation under there.