Jack,
It sounds like your main goal may be a "natural swimming pool". I think they are much more common in Europe, but there are certainly people in the U.S. building them.
I included a link to show you the concept.
https://www.motherearthnews.com/diy/natural-swimming-pool-zmaz02aszgoeYou design your pool/pond to constantly circulate water through significant plant zones that work as natural filters.
If you like that idea, you should be able to find quite a bit of literature on how to achieve your goals.
I do not know of an expert on Pond Boss in that particular field. However, there are a lot of people in this forum with an exceptional range of expertise and talents.
Good luck on your project,
Rod