All Gauges, Running lights, Interior lights, Bilge pump, and All Trim switches really should remain powered by the engine cranking battery.
Simply swapping over the Acc battery leads to a separate battery will negate your voltmeter, kill any additional trim switches except for the one on the throttle arm, negate a trim guage (if so equipped), and will possibly fry your tachometer.
That modification is definitely NOT Wrench Approved (as if that mattered).