I used to solve these problems by making my own clothes. If you sew your own, you can make the necessary adjustments on the pattern before even cutting the fabric. If you are persnickety, you can then make a version in muslin, make further adjustments to it, and use the muslin as a pattern for the final version. For the even more persnickety, or people who like to design their own clothes, you can use a dressmaker's dummy.
I never went that far, but I got to where I knew automatically knew how to adjust each hip and more importantly, how much longer to make the pattern between the waist and the crotch. That's what the "stride" is: pattern makers, being much less prissy than sales people, call it the crotch depth. It is the key measurement in getting pants to fit. Get it right and all those other disparities are less noticeable and can even be ignored. Get it wrong, and your pants give you a wedgie and people giggle about your camel toe, or your pants are too low in the crotch and it annoys the heck out of you all day long.
My one experience with having a too low crotch is a bittersweet one. When I went up north for my mom's funeral, I forgot to bring black pantyhose. I borrowed a pair from my sister, and they worked okay, but the crotch was just too low. I pulled them up as high as I could, and then they'd spring back to where they wanted to be. All during the funeral and graveside service, they were a low level distraction. I finally took them off at my sister's house before we went to see my dad, bedridden with a broken hip, at the VA nursing home. He asked how the funeral had been, and then looked over at a postcard hanging on a bulletin board opposite the foot of his bed. "You know, I kept looking at that all night long," he said. "That was the longest night."
"I know, Daddy," I said. I hadn't called him Daddy since I was ten. I brought the post card over to him. It was one I had sent him. He kept turning it over in his hands and it suddenly hit me - he no longer knew how to read. Since I couldn't reach him on the phone, either, I no longer had a way to communicate with him once I left.
Three weeks later he was gone.
One week later I attended a workshop on powered wheelchairs, sponsored by my place of employment. The presenter started out by discussing some sensory issues that affect fitting someone for a wheelchair. In discussing the tactile system, she looked out at her mostly female audience and decided to use the example of low crotch pantyhose. She described all the gyrations woman go through to try to adjust pantyhose, in the process miming brushing up against a table while trying to look nonchalant.
It was one of those moments where you either laugh or you cry, and left to its own devices, my limbic system immediately chose laughing. Loudly. And longer than anyone else in the room.
Later at lunch, a coworker told me that it was good to hear me laugh again. That's what her words said, but her face said, "Didn't your mom just die last week?" I decided not to explain. I was afraid if I did, I'd start crying and not be able to stop until the end of the day, or the week.
Back to my shopping trip. I tried on both the average and short lengths of the pants I wanted. The short version fit in the legs, but was definitely too short in the stride. The average length fit in the stride, but needed hemming. Fortunately I know a reasonably priced tailor. As I tried on the pants, the memory of the low crotch panty hose came back to me. This time I just smiled.