Use a wet and dry vacuum
and a short piece of 1/2 PCV plumbing pipe. Be sure to cut a couple of v notches in the end to stick through the inflation port. The notches will help prevent the tube from sticking to the inner wall and stopping the flow of air and water.Tilt the dinghy so the inside of the tube nearest the inflation port is on the low side so all the water pools unter the vacuum pipe.The longer you leave on the vacuum, the dryer the inside will be.Fair Winds