I have seen some posts somewhere which showed a mod for the Oasis which mounted a 2nd mast base tube via the screws that hold the forward hatch in place thus turning the Oasis into a schooner (2 masts - same size)
I think that must be an excellent addition as it will provide more sail area per kg of ballast than a standard sail on a single kayak & I would definitely make the mod if I had an Oasis - unfortunately my double is an Outfitter & doesn't have a front hatch nor space for a 2nd mast base so I will have to make a jib instead