Personally, I would run your electrical channel above the windows, or closer to the top of the bus. Centerline roof would be best, but you've got the cutout exits there to run around.
Running your electric up top will: a) keep it far away from fluids of any kind, b) allow you to branch off where needed for various circuits, c) your electrics will probably require more frequent modifications and additions than your plumbing will, so it should generally remain easier to access than conduit of some sort buried behind furniture which may or may not be permanently mounted or otherwise a major PITA to remove just to tap into a single line, or make a drop.
If you keep your plumbing tightly constrained, you could run it close to the coolant lines to help keep them from freezing, but the contamination is a risk I, personally, would not want to take.
Your access panels are commonly located on the driver's side, towards the rear, at least in smaller rv's, larger buses will be located in the rear, but closer to the mid-point.