May I ask whether this area in the Main Gear compartment is accessible for checking, and indeed is it a requirement to check it for damage at all during post/pre-flights.
According to the AIB report on G-YMME it had flown 53 sectors with this panel off and had only leaked because 43.000Kg of fuel had been put in, enough to leak during climb out.
After any tank work I always used to completely fill the tank in question for leak checking, but that was in the military and the tanks were only 9000Lbs max. This tank I believe can hold 80-90,000kgs
Thanks