Ah, the old debate... you're relatively new here so hopefully the wrath of the search mongers will not fall too heavily upon you. The idea of pilotable capships has existed since modding FS was possible, but the HUD is not designed to handle the number of subsystems. The game crashes when more than like 8 or 9 are damaged. However, if someone were to design and build a capship with all of its main firepower forward (with gunpoints, not turrets) then SCP implimentations such as fighter beams would make this possible, if not somewhat unwieldy. As it stands though, you could fly anything (until getting turret damage) but you wouldn't have control over any of the weapon systems on board.
The other issue is that, unless the model was specifically designed so that the bridge was on the extreme front of the ship, it would be a little hard. Most of my models have the bridge near the back, and if you were sitting there you should be able to see the deck of the ship sprawling out in front of you. With the way the HUD is drawn, however, the player ship will never be rendered, even if there are faces that should be visable from within the ship.