And here it is. My hubby and I have exactly the opposite fitting challenges when it comes to making pants. Can you see how different our shapes are from the side? His waist sits very low, while mine is quite high. The curve of his buttocks starts almost immediately after his waist, while I have a "ski slope" (Thank you Heather, for that term) down to my actual butt. The shape of his butt is much more round, while mine is flat. After having this epiphany, I realized that this was why I was having such trouble fitting his pants. I was trying to make them work like mine, and they don't.
So, for my low-butted, long & high waist, the alterations I make are these. This is Jalie 2908. The orange line is the original pattern, and the red is mine. You can see I raised the waistline - an inch at CB, tapering down to 3/4 inch at the side seam. The front is raised 3/4 inch all around as well. For the crotch, I have to scoop out the curve to allow for my lower backside, but since my butt is flat, I don't need any extra space down there really, so I leave the hip line and the crotch hook alone.
Here is the final muslin, with the changes as above. I could probably tighten up the fit in the thigh area, but Mitch likes his pants on the more relaxed fit side, so I'm leaving it for this first version, which I'm making in a pretty stiff cotton canvas. Hopefully, I can show you the fruit of my labors soon.