I was hoping that the service manual would shed light on a way to display voltage on the digital dash but no luck. That's not to say it can't be done it's just the Honda service manual I have does not list this.
I do understand the concern with an EFI equiped engine (PCM, fuel pump, etc). Maybe a battery isolator switch would be a good investment, just never known anyone to have problems with the charging system on a honda (ATV, Bike, MUV).