I'm not opposed to new pirate groups or anything, however, I think there are a couple things that should be considered before following through with this here idea.
A: The 'Reaver' name is already taken, so you may wish to find something that isn't already taken.
B: Declaring open war on the Navy whilst operating mainly within the House (Country) that they are tasked with defending, is not wise.
Think of it like this, say a group forms in the United States and goes out and starts attacking US Military bases in the United States, it does not end well. Now just replace United States with "Liberty" and US Military with "Liberty Navy" and you have yourself a good idea of how things will go.
Of course, you can be an enemy of the group and all that, but you honestly shouldn't go out of your way to throw your people at the Navy, because that's effectively a small group of pirates throwing themselves at the Military that defends an entire nation, not smart. only group in Liberty that really goes out of it's way to do things like that is the Hellfire Legion, because they have the resources to carry out an operation of such scale.
You really shouldn't see a small group of pirates trying that sort of thing...
*shrugs*
That's just my opinion though, you can do with it as you wish.