In addition to what's already been stated:
The RC IS hoppable with normal mara,
Zapping medi will zap both nodes, RC, armo, and I think 3rd to 5th rets from left,
You could just zap the edge ret from below and hit the other 2 rets next to it.
It is very difficult to build a mostly non zappable base in that place, since currently zap seems to hit everything in a cube shaped area, not sphere, and always does full damage, even if the other buildable is just barely in range.