Nick,

I think the idea you are looking for goes by many names: swimming ponds, living pools, natural pools, etc.

There is an entire culture of people that do your idea at their property. IMO it is mostly DIY since it is rare enough that it would be difficult for a full-time contractor to make a living doing ONLY that type of work.

The link below shows some excellent examples of the concept and also explains the fundamentals. Once you get the gist, you should be able to search for many more source articles.

Natural Swimming Ponds

I have researched this type of pond for our property, and did wonder if it could be optimized by adding some filter-feeding fish. Would tilapia or threadfin shad make that type of pond even more clear?

I think the strength of Pond Boss is the available expertise on "fish ponds". If you get really serious about the project, maybe start a new thread and ask the experts about deliberately adding filter-feeding fish? I don't believe either TFS or tilapia are known for nipping at swimmers.

Good luck on your project!