Sorry I can't provide any wisdom here as I am in the same position with my Morgan 30. There is no space forward of the water tank in my case, but both the port and starboard under-v-berth spaces look possible. I was originally hoping to locate the tank somewhere on the centreline, but that ain't a goer. I guess it would be possible (but more complicated) to install a tank on each side and interconnect them....
Have you decided what make of tank you are going to use?
Leith (rhymes with teeth) is the port of the City of Edinburgh in Scotland. A Leither is someone who comes from that area.
I must go down to the sea again, to the lonely sea and the sky - I left my shoes and socks there, I wonder if they're dry?