What does the residential Boat Owners Association (RBOA) have to say on this subject. I would have thought that as you have to obtain a Licence for your boat you are registered with BW and if you are a Continuous Cruiser you register as such, so not homeless then ? You have a named boat with a registration number and a licence stating that you are a Continuous Cruiser (Liveaboard).
Now I can also see the problem for the authorities, without a 'conventional' static residence with a letterbox they have difficulty in knowing where you are at any given time and where to send correspondence. But if you are able to use a permanent address of a relative or freind to which mail can be sent, up to you how you then receive it, there is no reason why you cannot be on the Electoral Register (Edited or otherwise), you will then be able to have a credit rating and you could receive voting papers and lots of other correspondence. You would only be able to vote in Local or National elections at a polling station in the constituency where the permanent address is located and it would be up to you to get there to vote (unless you elected for someone to vote on your behalf - Proxy vote). As I see it, this country is only set up to cater for those who live in a 'conventional' environment. However, we already know that when we decide to take up what is still regarded as an 'Unconventional' lifestyle and therefore must surely expect to have some challenges with that lifestyle. At the risk of being 'lynched' I am not saying that this is right and should not be changed but change takes time and means changing attitudes to what is considered 'Conventional' in a modern society.
As I have said earlier in this thread, you are not alone in the 'unconventional' lifestyle, the Motorhome 'Fulltimers' have very similar issues. Probably a little worse off in some respects as their vehicle may be registered with DVLA, but this has to be to a permanent residence and there is no Road tax coding or otherwise for the equivalent of Waterbased Continuous Cruisers. So it is just another motor vehicle. They also have similar problems with being continually on the move with the likes of registering with GP's and Dentists and trying to get repeat prescriptions.
Irrespective of whether water or land based, called 'Fulltimers' or 'Continuous Cruisers', the issues are very much the same. Therefore if a co-ordinated approach could be made to the authorities at the highest level, it would soon reflect that in fact this so called 'Unconventional' lifestyle is actually a widely adopted lifestyle and there should be more effort made to cater for those who adopt it. Unfortunately, there is no organisation like the RBOA within the Motorhoming fraternity so representation is currently conducted on an individual basis. It reminds me of the old addage, "United we stand Divided we fall" or as I tended to put it, "There is strength in numbers".
Sorry to have woffled on but it is a highly complicated area, but should not be one that is impossible to find a solution to, just needs good organisation to take the issues to the correct level in Government in a calm and rational manner. Also would be a good strategy to show benefits to the wider society as I am sure you will be aware, when negotiating there is always the question of "What's in it for me".