I'd stay away from epoxy since it may be a PITA to remove it if you have to. How about using something like the wax around Babybel Cheese. "The wax that we use for the coating of this product is made up of an appropriate mix of paraffin wax and micro crystalline. There is no Bisphenol A in the wax" or just use a waterproof enclosure like offered here http://www.okwenclosures.com/enclosures/waterproof_enclosures.htm?gclid=CIqI2Ommh6cCFZJa2godbSNedQ then you only have to content with one slot you may need to create for the USB cable. Just my 2 cents....good luck and stay dry :-)