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View attachment 231817
IMO that looks like a decent job blending fuel tank into bottom of fuselage and it's positioned not to upset aircraft balance. Something similiar might have worked for long range escorts such as P-51D or perhaps a long range Spitfire.
Weight in the wings helps counterbalance the bending in the wing due to lift.
I can see that wing tip tanks will restrict roll rate, particularly when they have fuel in them.
True - but one of the first things a stress analyst will look at is a high G landing with full fuel.. lift at minimum, max down load.