Use an Ag Leader clutch module to run the system. Have the module run a set of relays. Constant power to the coil and ground the coil to the module pins 1 and 2. You can use the high current circuit on the Ag Leader implement harness to power the relay contacts and the clutch solenoids. Put an additional power cable on the tractor and power the clutches off the black plug if you want to keep the clutch power on a separate circuit from the modules. I usually fuse the clutch coils at 15 amps. 

I wouldn’t even dream of putting a battery back there. The draw in coil pulls current for a very brief time. The hold current is very very minimal. No need for a battery.