SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I'm in the process of designing and installing a system in the front yard and the back yard.
I live on a lake and will pump from there using a 2 hp pump.
During construction of house I pulled 7/c control wires from the garage to the potential site of the timer in the rear of the house. I now determine that I don't have enough control wires to furnish entire system. Pulling additional control wires to the garage is impossible.
What I plan to do is to install a timer for the front yard and a timer for the back yard. I have a pump relay to be wired to the timer in the back yard. I plan to pull additional control wires to the front yard timer to control the heads.

My question is:

Once I complete wiring to both timers how will I control the pump for the front yard timer? My thoughts are that I can operate each timer on alternate days but I think that I will have to run control wires from the pump relay to the timer in the front yard.
My biggest fear is that a malfunction could occur and that both timers would try to operate at the same time.

Is my way of thinking right or do you have a suggestion that would make it more simpler to install and operate.
I had considered installing a timer in a waterproof box outside but
I don't particularily care for that idea. Thank you for your assistance.