IMHO the Royal Navy is one of the most under utilised features of the game. I think it would be more interesting if the RN actively moved around and went 'hunting' for the ship and maybe even the homebase. This way you would need to plan the exploration trips a bit more carefully and introduces a bit more strategy. This could be brought in when either the base or ship is above a certain level or be an opt in feature. I'm curious about how my ship would fare up against 2 or 3 RN ships in one go....
Interesting idea, I guess it would require some fundamental changes and balancing to make it work however.
I think it would be interesting, but ultimately frustrating. If they did implement it I think it wouldn't be too hard. Just have a standard ai and boundaries for each ship and let them move at the same pace our ship currently moves.