I have the original tank that came with my 22. It is the poly one. I'm not using it. My plan is to put one under the v-berth area. However, I have had it out for about 3 years now and haven't missed it. The storage space in the cabin where the tank was is much more useful.
I'll be out of the country for awhile, but if you're interested in this tank, we can try to work something out.