Stuck Between Two Itineraries!

My fiancé (25M) and I (25F) are traveling from the US to Osaka in May of 2025. We’ve done Tokyo and Kyoto before, and we’re looking for a place that’s a bit less touristy and bustling city, with some scenery as I’d like to hold a little symbolic ceremony outside in a pretty spot. My Japanese is enough to get us around a language barrier for ordering and directions, but we’re planning on also flying out our close family (siblings are parents) to watch the ceremony and so my elderly dad (80M) can give me away. My dad's mobility has declined quite a lot, so I would like to find a location that isn't so rural that he won’t be able to easily get around, even if we might have to have a wheelchair for him.

If flight prices stay reasonable, we’re planning on landing in Osaka (KIX) May 20th, and leaving June 3, 2025 (two weeks total) to avoid both the busy and the rainy seasons. I have two plans to decide from. Plan A is to follow the interstate 42 along the Kii Peninsula coast and loop back up to KIX by the end of our stay. Plan B is to go west to Okayama, then down to Tokushima, and loop back to Kobe before we leave. We would love some advice on some private outdoor ceremony spots along these routes, so we can build the rest from there.

**I want to be clear that we are not looking to have our itinerary planned, just looking to find a secluded outdoor spot that would be pretty enough to hold our ceremony without bothering any tourists or being in the way. We will be planning the rest of the trip around this spot.**

Thanks Reddit! P.S. the ceremony will only be symbolic, as we will be signing papers legally back home in the US. Also, I’d prefer to avoid holding a ceremony in or near a shrine or temple because we are not Japanese, and I do not want to disrespect Japanese culture, but if you disagree, please tell me your opinions!