Altering/purchasing RTW denim/pants to fit sway back + sufficient derriere

I found this *awesome* illustration that quite defines my figure (see image). My waist is a size 4, my hips are a size 8. However, it's not a fix that involves a slight taper down the hip line, it's really the *massive* jump from my back to the protruding shelf, er, derriere that is nearly impossible to fit. The front and side hips are always fine. I've found that "super low cut" jeans really fit well, because they're cut below my "sway," but then reveal a whole new world when bending over. ;) Unfortunately I've also found that maternity jeans fit gloriously, because they flatter my hips, and don't have a gap waist. Odd, I know. Point being… I need to buy jeans that fit my hips, but how on *earth* do I tailor the back-only of the jeans?? The front waist is always fine, it's just that protruding issues. I'm at my wit's end, finding a solution that is quite lovely, and not looking like it's hacked. Thanks!!