The Mossie had a crew of: pilot and navigator/bomb aimer or navigator/radar operator.
I'll say it again,
replace the American heavies, especially the B-17. This would give a surplus .50" guns which could have been fitted to the Lancaster. The Lancaster was needed for its heavy lift capacity.
"In 1941 the average bomb load per attacking aircraft was 2,889 lbs whereas by 1944 it had risen to 9,155 lbs according to ACM Harris' Dispatch. In the official history the average bomb load of RAF bombers is given as 6,903 lbs in 1943, and 8250 lbs in 1944, and the corresponding figures given for the US AAF were 3,220 lb and 3,980 lb respectively."
http://homepage.ntlworld.com/r_m_g.v...Offensive.html
Can you expand on your statement JoeA?