Two way water heater question

[LRL]

Our new E23 has a two way water heater - which we love but which is a new concept to us. The electrical “on” switch is located outside, under the panel covering the water heater “guts.” Rather than go outside to turn it on all the time when needed, then remembering to turn it off when off of shore power, I’m wondering if it would be OK to leave it “on” all the time. When not attached to shore power, I’d use propane by switching it on from inside the trailer. When attached to shore power, I’d just plug in and the water heater will begin working.

Is this safe and OK to do, or do I need to turn the shore power switch off and on as appropriate…and make sure it’s in the off position before using propane?

Thanks!