Hi-Dee-Ho
The "guild vs guild" thing isn't quite our style, but if individuals from the guild want to participate, go for it. Just know you're not representing the entirerty of Dueces if you do
As for directing people to POF, I've never had a problem with saying "pirates on line forums" in game. I've gone as far to say, "you can find us at pirates on line forums, we're a sub forum under dueces wild"...all good so far. Before you direct people to pof, you may want to set up a thread in the general guild section (not here in the Dueces section) with what you're looking to do.
Best of Luck!