Idk why your panel is only 3/8. How we do it here is we layer like 3 pieces of 5/8 sheetrock then put rigid foam on top for insulation then build like a little frame on bottom for it with 1x4 kind of like trim to keep the hatch seated/so it doesnt fall down. Idk how to make it latch though. Maybe put one of these bitches on it.