Im thinking probably the best thing you could do is screw some boards onto what will eventually be the underside, then flip it over to the topside, put some linseed oil or tung oil on. Only on the top side. Tuck it away somewhere, sticker it, put some weight in it and wait for a while......it will take around a year per inch thickness to dry out..... Then you can remove the boards and plane/sand it to desired thickness
Um, no, Dennis is not 6' but not too far off. Scotty Overkill on left; Dennis on right. Scotty is much stronger as he only needs one leg to stand on and I have 3.