Great story, and great first trip with your new tenkara rod. You will find with time and practice that casting a soft tenkara rod, and the Ayu is one of the softest, is all finesse and no force. Even after backing off on the strength you are probably still overpowering it. You do need a bit of acceleration and then a hard stop, with the rod tip still at 10 or 10:30. Most casting problems are caused by stopping the cast with the rod tip too low and not having a well-defined abrupt stop to your forward cast.
There will always be fish just out of reach but you will find again and again that you can catch a lot of fish that are much closer than that.
I think you're right, though, I think you will like this style of fishing.