Other than dealing with tree roots and boulders, I don't see a problem. Just ensure your predator proof apron either goes down into the ground a consistent distance, accounting for slope, or lay an apron on the surface a consistent distance out from the walls.
If it were me, I would cover the walls to the existing ground/slope level (bottoms of the fencing/wire will probably look a bit like a staircase), then tack on a separate apron out from the walls along the surface. That way you can somewhat follow the slope of the ground with the apron without it looking super wonky by needing to angle the wall materials. Does that make sense? If there is a 5 degree slope, you don't want your walls to have a mesh pattern that is tilted 5 degrees. Would not look good. But an apron tilted 5 degrees wont be as obvious or easily seen. Just do the apron in small chunks and overlap the mesh where pieces intersect.
