I am in the process of rigging my Triton 21HP for a 250ss Suzuki. Due to the way my dash is shaped I installed a Suzuki 4" SMIS gauge. My boat has a nmea system setup already and is powered on by an accessory switch. I am going to install a power isolater so the gauge doesn't stay on the entire time and is only on when the ignition key is on. My question is does the Suzuki interface need to be on key powered also or can I leave it on with the accessory side of the nmea network?