Ways to travel from Kyoto to Naoshima

Hello, what is the most stress free way to get from Kyoto to Naoshima for 5 people with luggage? I do undertand that everybody in Japan travel by train, but we are on a long trip, all with large heavy suitcases and smaller daybags/backpacks. Changing two busses in Kyoto, than taking Shinkansen and another train to Uno Port, then taking a ferry, then a local bus seems tiring and complicated with too many changes. It does not seem to be worth in order to spend just two nights and then go back.

Are there any private transfers or helicopter charters for the route, or should we better rent a car and drive?

Helicopter rides from Kyoto to Naoshima are offered from 880,000 yen by this company:
https://lp.airos.jp/naoshima

I myself would never take any large suitcases anywhere onto the streets or onto public transportation, and instead send them ahead of you strategically from hotel to hotel.

Also, avoid buses in Kyoto whenever possible, especially with luggage. The local bus system has always been insufficient for the size of the city, causing the tiny, infrequent buses to be packed with people all the time along the popular routes. Use rail-bound transportation and taxis instead.

Without suitcases, the trip from Kyoto via Okayama and Uno is a pleasant one, offering much variety first with a shinkansen ride, then a local train ride through rural landscapes and finally a ferry ride.

If you have day-bags, then ditch the big cases or use luggage forwarding. Even for a long trip (a month or more) many people travel with a single carry-on bag. You could either send to Naoshima or your next destination.
In Kyoto, consider a taxi rather than two buses.
And, yes, if you want to visit somewhere off the beaten path, it does take a lot of transfers. For Naoshima from Kyoto that means two trains and the ferry. There are two taxis on the island. See if you accommodation offers a transfer from the port.
Renting a car - that's going to take a long time driving and if you have your five big suitcases, you won't get those in the back.

Large suitcases are a nightmare not only for you, but also for locals. This is especially true in places with high concentrations of tourists like Kyoto.

https://www.youtube.com/watch?v=JjRxioAtRXI

See from around 0:26.

In Kyoto, you should not stay in a hotel where you have to take a bus. Probably more than 80% of hotels are located close to an underground, JR or other railway station, so there is no need to take a bus to get to/from Kyoto Station. Tourists should not take buses to and from Kyoto Station. Of course, this is something the administrative authorities may not be able to say, but that is my personal opinion.

The Youtube video mentioned earlier has many Japanese comments, many of which blame the government and local authorities for their inaction, and there is clearly some irritation towards foreign visitors. Although many foreigners come to Japan, 80% of the tourism income is still carried by Japanese people, and Japanese people basically do not carry large luggage when travelling within Japan or send it by courier, so the picture is that only foreigners are travelling with large luggage. This is unfortunate for both foreign and Japanese travellers.

Reducing luggage, this is of primary importance. Most hotels in Japan have washing machines and dryers (this has become more pronounced in the last decade or so), so if you have 3-5 days' worth of clothing you can cycle through it and wear it. The next step is to use courier services, as has already been pointed out. Courier services cost around 2000 yen per item and can deliver almost anywhere the next day or two.

Either travel with daypacks (a 28L should be large enough for 2-3 days worth of clothes) or stopover/ stay in Okayama.

The stopover in Okayama is probably the better option as it means you won’t be losing daytime hours to travel (9 - 5) you can also use your travel day from Kyoto to visit Himeji and Kurashiki. Staying in Okayama you can get to Naoshima before the museums open.

As others have mentioned traveling in Japan with large suitcases is a hassle. It is better to travel as light as possible. A lot of accommodations in Japan have washer/ dryer available.

Thank you very much for the answers. I did not know about luggage transfers, because it is not very common in Europe, where I come from. It is definitely worth considering.