Given no conditions against you in your SOPO then you would have to understand where the Police Stations are that you can go and register each week; if the boat is moveable and you will be travelling that is.
My scenario works on what I was informed by a PPU when I considered it as it is classed as a non-permanent address, Think of it with the understanding you cannot register an address you do not permanently reside at, as it is not the building as such it is the location the building is on that is permanent. A building can be removed and rebuilt so the address stays the same.
What has your PPU said to the concept; though if your conviction is fresh they may be cautious as they may feel they do not know you even to say anything else.
Learn from yesterday, live for today, hope is for tomorrow else what is left if you remove a mans hope.