I run a JR voltage reg on one LiPo pack for the Rx and then one pack for ignition. I use air retracts. So for the switches I use the Mpi charging switches on the left side low above the wing. Front for ignition rear for Rx and the polarity matches with ground to the rear. This is how I check voltage and charge with the wing on.
To make a hatch on this plane I'd say you could cut in front of the canopy windshield where the real fuse fuel tank would be. This way you have access from within the fuse to build the hatch before you cut it free of the fuse. The build has a lot of stringers for construction so you have to stabilize the section of the fuse before you cut it.
Do you have razor saws like from Zona or Xacto? I like these the best for cutting hatches because you get very clean narrow cuts.