If you want your ship to look good and be great at pvp you need to start from the outside in, and by that I mean build your frame what it looks like on the outside then thicken the walls 2-3 times on the sides bottom top and about 5x in front, then hold n connect to that ship and enable centre of gravity sometimes it doesn’t show straight away, it might be a bug but when you finally see it you will notice 2 speres on the line, one will be center of ship other will be center of mass according to weight distribution.
Best thing to do is build a 3x3x3 cube of RCS 2’s right on that center of mass the blue sphere as this will give your ship very nice turning speed. From there I would mark out where you want your cockpit close it off with blocks so you don’t accidently use that space for other modules, make an entrance to it and leave enough space for what ever you need, then with the rest of the space place 4-8 Large 3x1x1 Reactors in different parts of your ship making sure no 2 parts touch, then do the same with your thruster’s split the same direction thruster around so they aren’t too close to each other same with fuel and o2, try get your ship to 22-40m’s in all directions, if you don’t have enough space for that you can get away with about 30 forward thrust 15 upward thrust to get off the ground on heavy gravity 20 side to side 8 down and 10 backwards as breaks.
From there I would place about 10 Large 2x1x1 Ammo crates and fill the rest inbetween all those modules with solid cubes to protect them one your hull is breached, redundancy is king in pvp the more backups of each you have the longer you will hold.
I wouldn’t build a Hanger door on a PvP ship even as a carrier as someone with their sv can fly into it and bug out your ship it’s a massive weak point’s. If you want docking points I suggest at the bottom of your ship leave a flat area with a elevator shaft and door under it and have docking pads on the top of your cockpit so when you dock and exit your vehicle you can move upwards through the door with blue barrier into the elevator shaft and be safe from temperature and radiation.
With Outside guns It’s best to stack them cascading like steps so that no turret is facing the back of another and unable to fire, so usually a thin front and thicker back of a ship will provide you with the most firepower. Also most people use the max cap of every single gun available but this could be their down fall as its very ammo inefficient, It’s usually better to choose a few gun types that you like using Eg for me its Arty + Pulse + Rocket + Cannon and have only those ammo type’s, you will run out of ammo long after your enemy that uses everything will.
Another thing is to sink your turrets slightly into the hull so that they don’t recieve a lot of fire, but you need to leave enough space for them to still have a decent angle of fire available else your nerfing your dps Also make sure to go into p menu and setup what you want each gun to focus on firing at, having too many options per gun will split your dps too much over the surface of the enemy ship, and focus fire is always a lot stronger in pvp encounters.
Sorry for wall of text 
but I hope this helps.