I for one would Love some US ship girls, as OP as they might be. (Night attack carriers, Subs that can Fight other subs, Dam con worth something.)

There are a few things that concern me when it comes to adding non-canon ships, especially allied ones.
First, they don't have an actual place in the world itself, which closely resembles japan during WWII, they'd need some kind of story exception to explain their presence. Story-wise the Shipgirls are also sensitive to ships which they have a negative history with.

Second, everyone likes KanColle, but not necessarily everyone likes Warship Girls.
I'm worried that US ships will come to play a too big part in the game, which would mean that we'd stray further from the source material.

My immediate priority will be the remaining KanColle shipgirls, after that we'll see..
Not to mention Kai-ni ships.

And you can't add US ships without adding fletcher, http://vignette1.wikia.nocookie.net/warship-girls/images/c/c2/Fletcher.png/revision/latest?cb=20150508075226

Right now I play both warship girls and kancolle. It would be great to have US or British warship girls in trpg

I would absolutely approve of it, though ideally as a separate mod somehow. Maybe put them in their own boxes, or perhaps (and this might get cumbersome) have a second Workshop upload for the version of the RPG with these characters.