I think that there is no longer any reason to keep the last ship of a player not lootable. Especially by the the time that this last ship can be an unsikable Man'o'War.
Firstly, it does not make any sense thus creating special unneeded rules (you say you don't like many rules, right?)
Secondly, there is a way to get a new ship cheaply, in case you lose it (it wasn't possible at the game start, was it?)
Thirdly, a Man'o'War can play a big role when attacking trade fleets, even if these are well armed and even if this is a lvl 1 man'o'war. (How traders are supposed to defend against low life pirates if they got an invincible man'o'war?)
For these reason, I suggest that you lift this kind of protection and make the last ship of a player lootable.