Having completed the front, drafting the back seemed reasonable even familiar except for one thing and it blew my mind. Let me tell you about the experience.
Simple enough to start. Copy the front onto a new sheet of paper. I included the frame-work (black) which wasn’t necessary but felt comforting. Yeah, I’m weird. Then copied the front (orange). I made my guidelines/other marks and initially my lines all in pencil. Then after checking and rechecking, traced over the pencil in turquoise green. Guess what had my eyes bulging:
If you said “crotch” we’re both on the same page. Suzy gives a specific formula that is for everybody (calculated back hip divided by 2 then minus 3/4″). Mine was 4.75″. WOW. In a way it makes sense. I am forever scooping and extending the back crotch. Also do you really know any curvy/plus sized woman who is only 2″ deep (as you look at her from the side)? Well for years that 2″ was all I ever say on a paper pattern. Doesn’t it make sense to you that a curvy girl needs more seating room than most people? I’m almost OK with the 4.75″ inches, except I needed a very sharp curve to connect crotch point to thigh onto knee. It is such an odd shape that I stopped to recheck all my marks and calculations. They are right on. Someone is going to remember that I use my High Hip measurement instead of low hip because my tummy is larger. The difference is 1/8″ which would require the curve being 1/8″ deeper. I don’t think that helps.
Using Suzy’s directions, I end up with a lot more ease along my entire leg.
It is no longer a close-fitting leg. After the thigh, the rest of the leg finishes with 3 or more inches of ease. We’re getting into trouser territory here.
I am a little uneasy with the torso portion.
The waist slants upward, which I was not really expecting and the crotch slants towards the center of the back. Possibly that is because of the dart and method of its adding. You measure over from the side seam half the width of the waist; add a 1″ dart; measure over to the other half of the waist. That becomes the top of the back crotch. The back crotch upright is higher than the front because one of the first things Suzy has you do is extend it 1.25″. Between the two procedures, the waist and crotch upright are unexpected, at least to me. Possibly if I had measured from crotch upright over; added dart and then measured the rest of the waist the crotch would not have the slant it does. I think I understand what Suzy is doing. She is adamant that the side and inseam of both front and back need to be alike for these seams to hang nicely.
There is still another lesson in which the back and front are trued. Suzy promises that both back and front will change again and it could be drastic. So for now, I’m just going with it. But I’m reluctant to make even a muslin with a crotch like this:
sdBev's Pants! 
I have done a lot of work with the Furrer pattern draft. The photo of your back pattern overlaid on the front is not clear but when I look at the pic of the front it appears that the knee is not centered on the grainline — there is more distance from grainline to outseam than there is from grainline to inseam. I’m pretty sure that is what’s causing that extreme curve. My back extension – using Suzy’s method – is 5 5/8 and I do not get an extreme curve. Hope this helps!
This something I can definitely check. Thanks. Nev