Duel shower heads

I just ripped out my bathtub and am making the area into a shower. Since the area is so long for a shower, I was thinking of putting shower heads on both wallls, only issue is the main big wall is a outside wall and im worried about freezing a pipe. Im in Tx., so it doesnt get that cold but we do get some low 20's and teens in Jan. and Feb. The main water supply comes from a inside wall thru the floor. How would you rout the Hot and Cold to the other side??

First I though cut a notch thru the back wall studs and wrap the copper pipes with that pipe foam stuff. I also thought of going up in the ceiling and down but the attic. I also had a passing idea to run the 2 pipes in between the curb I have to make for the shower since that area wouldnt get cold. Any thoughts?? I doubt if any would be up to code but im looking for functionality. lol

What's in that bulkhead above the shower...a furnace run? So long as you keep the valve and pressurized piping where they are, I think you will be fine so long as you pipe things properly and keep the runs behind insulation. If you are really paranoid, you could install a toe tester which would allow the showerhead lines to drain after use...so long as you sloped the piping properly.