Have you shortened the entrance hatch Bill ?
Although the hatch is under the turret post, there was still plenty of room to gain entry.
Far as I know, there wasn't a hinged 'floor' cover over the forward, outward opening hatch, although there was on the rear hatch.
I recall a RAF aircrew member account describing how he stood on the (forward) hatch to move up into the cockpit, and it fell open, but not fully due to the slipstream, as it hadn't been properly latched. Fortunately, he was able to close and lock the hatch.