Koyasan to Hongu - River boat then Shingu?

Hi everyone, I am just in the midst of my japan trip planning. I am just confused on what is the easiest way to do this section of my trip without doubling back.
This is what I want to do:
- Travel from Osaka to Koyasan, stay overnight in the temple stay (worth it?)
- Travel from Koyasan to Hongu, I want to take the riverboat down to Shingu but it looks like the 9:45 departure from Koyasan means I would arrive at 2:25 in Hongu, before the boat stop, and would miss their 2:30 trip. Should I stay in Hongu for the night then take the morning bus to the boat stop? Is staying in Hongu area worth it?
- Take the boat down to Shingu, see the Kumano Nachi Taisha Shrine, there is a lot in the area to see, yes? Would half a day suffice or should I plan another night there?
- Travel from Shingu to the airport and fly back to Tokyo


How do i make this work? is there a more smooth transition? Am I missing something? Thanks.

When I did this trip a few years back, I had a World Heritage pass, and an active 21 day JR pass. I went down the cablecar, and went back to Hashimoto station on the World Heritage pass. Switched to JR. and took a liner train to Wakayama. I then took the limited express train to KiiKatsurra. There was a bus route that went from Koyasan to Tanabe, but my route was already paid for with passes.

I had never even heard of this boat route, and I am wanting to know more. Next year, I would like to do the same thing again, but I will not have a JR pass. I actually want to stay at one of the Onsens near Hongu, but I have not done so yet. Ifve heard they are good.

I have also heard that some of the Hot Springs Towns between Koyasan and Tanabe has Sodium Bicarbonate hot springs. So I might want to go the bus route to stay in Ryujin Onsen, instead on doing the river boat route. I am interested in knowing about the river option. Check out the Ryujin Onsen at the Tanabe Tourism website.

I can tell you that I did visit Hongu Taisha from Shingu, and the bus followed the river upstream. I thought the view from the bus was wonderful.

I can also tell you that there is an overnight highway bus from Nanki Katsurra Shingu to Ikebukuro in Tokyo, If that helps. Just use ghighway bus Nanki Katsurra ikebukuroh on a web search, and the route will pop up on Japan Bus Line. I actually like the hotel Urashima in Katsurra, because of the sea cave hot springs baths, and the tuna carving demonstrations at their buffet. I will probably stay a night, and go to Nachi Taisha, before taking the overnight bus back to Tokyo.

If you have a link to the river boat, Please post it.

I hope this information helps you, too.