Thanks to everyone who provided suggestions. I tried the Joint Editor with no success. I could get the bulge behind the knee to disappear, but only at settings which deformed the leg beyond recognition (as a leg anyway). I had better success switching to the leg stretch morph and eliminating the use of scaling, though my preference would have been to stretch the shin more than the thigh. (And of course, Vicky2 suffered major crosstalk disease on the leg stretch morph).

I also changed the displayed leg-bend pose from 0 deg hip & -65 deg thigh to -30 deg hip (the supposed limit) & -35 deg thigh. There's still an inappropriate flat patch near the hip joint on the thigh, but it's not as bad. And the weird bulge on top of the thigh is significantly lessened.

I may try Jim Burton's Glamorous Vicky, but I've already built and applied a number of my own magnets, and I'm not sure how well those would transfer to GV. I'd like to keep using my own magnets because they deform the V3 clothes as well as V3 to maintain the fit.

But maybe I won't scrap V3 just yet.

Again, thanks to everyone...