Staying elsewhere when checked in

Hi
Have an upcoming stay for a about a week in a minshuku in Ishigaki but I plan to make a visit with sleepover to one of the remote islands if the weather is alright (ferries might not be running).

Would it be appearing as ride to the hostess of the minshuku if I did not return for the evening?

I have no dinner included or so in the stay. Just a room.

I find it a bit if a hassle to manage with the luggage if I would have to cancel one night in the middle of the stay. I would probably not get any money back for the cancelled night either due to cancellation policy.

It is not rude if you notify the owner of minshuku.

According to the hotel policy, you have a set day to cancel you hotel room, even if it's in between stay, there shouldn't be any problem, just tell them you will be out town for that day, and since you will be staying in the same hotel then next day, most hotel will allow you to keep your luggage for your return.

In the past I have booked one accommodation for 5 days and also another in another town for one night. I told the 5-day hotel I will be staying away for the night and they were more than okay about it. As long as they're notified (so they don't get concerned about your absence) and you have paid them for that night, you are alright. I did it that way so I didn't have to travel to the one-night hotel with all my belongings. It surely helps.