The gunboat forward gun works on a much larger scale than fighter sized weaponry, hence why it's that much more powerful. If this thing is going to have one of those it needs to be fully dedicated to that gun, and that gun alone, meaning that it'll be nothing but a flying gun with minimal armor and shields due to the huge generator needed to feed the gun.
In short: The ship should only have a gunboat forward gun and nothing else, cause otherwise we're delving into the all too familiar pool of "LULWUTPWN" gaming.
