If you're a Tac in an Excelsior R you can do Ok if you bust out C:RF 2 or CSV 2 and AP:A and some DEM action...
Swap 2 or 3 of the turrets in your forward arc with single cannons it can be not too bad!
I know, 1 of my Tacs is flying a cannon/turret Excelsior with CRF2 + APB1 for a couple of months now.
The carrier instead is just for the show, it looks awesome and that's all what it is intended for. If cannons and turrets would have more than 1 fore and aft firing point it would look super awesome.