This is what I probably should have.
Ventrac - Advantages: Slope Mowing
Actually, I'd love one! They are spendy though. I think the one in the video with duals is about $23,000.
The hills are steep enough that I usually spin out if I try to go up them & over power the rear end if I go down. I can mow them sideways if I lean out on the up hill side. A co-worker of mine had the same type of terrain and he actually broke out the center of the rear wheel on his MTD mowing sideways. Granted, MTD.....
I'll either try to get some pictures tonight, or some measurements.