It appears that you machined a 45 degree bevel on the inside contouring of your fuselage sides and bottom. The section A-A you refer to shows a much more shallow bevel. You MAY encounter problems of break-through when contouring the outside of your fuselage. You WILL encounter an awkwardness when contouring the outside of the fuselage at the seatback bulkhead/main wing saddle area. The plans show the fuselage sides contoured to a "knife-edge" thickness of foam at the longerons (page 7-12, Station 70.0 and station 89.0) but immediately aft of the seatback bulkhead that knife edge has no longeron to support its inboard edge (page 7-9) and you've carved away the foam below the main wing but ABOVE the level where that knife edge line would continue aft of the seatback bulkhead. The dashed lines in the plans on page 7-9 behind station 78.0 extend too high up the inside wall of the fuselage side, causing the foam to be carved completely away or a compromise carving modification that results in an awkward bulge just aft of the canopy. My advice, since you're already carved the inside of the fuselage sides, is to modify the page 7-12 station 70.0 and station 89.0 carving profiles to leave more foam outboard of the longerons so that a smooth external shape can be achieved aft of the seatback bulkhead. (Too many words!)
Wing foam: make sure your wing foam has large enough surface pores for a good mechanical bond of the wing skins to the foam.
Epoxy: I am told that MGS-335 is NOT adequately fuel proof for fuel tanks. Be sure to use EZ-Poxy or Derakane 204 (or newer variant) for the inside of your fuel tank.
