This sounds like a fun idea.
Of course, if I really wanted to get nasty in a sneaky kind of way, I'd outfit a standard Galaxy class saucer "Q-Ship style". That is with all sorts of concealed weapons which can be extended from the hull as needed.
For example, take into consideration those two enormous elevator shafts which run from the top to the bottom inside the saucer on each side. All that unused open space.
You could fit quite a bit of hardware in there. Think of a giant module or so which is "plugged" into the shaft. Just open up the outer hatches and let the fun begin!
Though the "Q-ship" concept is for a disguised merchant ship to be heavily armed so they can pick off destroyers, frigates, and perhaps even cruisers that operate as commerce raiders.
I doubt that any enemy ship would approach a Galaxy class ship without going in with shields up and weapons armed.