I got two 4S 5000mAh packs under the cockpit, there are two options here. If you don't like hatches you can use arming plugs, hook everything up, bolt on the wing and when you are ready to fly you just install the plugs and the plane is ready to go. I did this with my Royal Corsair because it was originally glow and I did not want to add hatches to it. Next option would be to add a hatch on the bottom of the nose, not as convenient but it would be hidden while on the ground.
I don't like your setup, but it's your plane, I was just offering my opinion.
I made the arming pin myself. My finished 1/8 Royal Corsair. I'm going to use one battery for the outer motors and one battery for the inner motors, ESC will be in the wing saddle.