Wingtip tanks and G-loads

They are attached much the same as B-17 wings are, multiple forged fittings at the top and bottom of the airfoil surfaces, actually extensions of the multiple wing spars. They were plenty strong enough, the weight of the fuel would easily be supported by the structure. With the tanks full, the wing would have less gust stress applied, when compared with tanks being installed in the fuselage.

The early civilian Lear Jet carried either most, or all of it's fuel in tip tanks, it made great sense from an engineering standpoint.

A good question. I spent about an hour reading pilot forums on this, and there's a lot of good information.

Summary seems to be, and this is for civil not fighters, that it reduces wingtip vortexes, can contribute to a thinner wing design, and can pencil out as lower power settings over the same time and distance.

They sound as though they make the aircraft more stable in rolls, which would not be conducive to fighter performance.