Wow, that looks super NFN! Bravo. I've used your technique of a white undercoat sanded off. For me it makes sense to not worry the details too much if the panel is well-recessed into the forward fuselage, especially when it comes to WWII bombers that have copious canopy framing. You just don't end up seeing more than the outline of the details anyway. That looks like a Mosquito panel in an earlier post right?
Open canopies in large scales are another matter altogether. Then I always try to get my hands on some PE, preferably a color ZOOM.