I got a EQ6 installed on my plane yesterday and I'm wondering if I can just use 1 singe switch to turn the unit off???

I was reading on the maual and you can install an optional Fail-safe switch to the FS input on the unit,,,will that let me just use only 1 switch or do I still need 2 switches beatween each battery???

Can just the pinflag switch work as a switch once installed there???

see picture...