Maybe build your frame work level, lowest point of framing at highest point of ground, and the HC will just go past the lowest horizontal framing into your apron?
You could attach some 'dummy' verticals below bottom horizontal where needed to attach HC before it hits the ground.
Hope that makes sense.
Yea, that makes sense and isnt a bad idea at all. I'll need to see how it would effect the "door side" of the run.