My pond is a very irregular oval. The middle section that has fairly straight long axis boundaries on each side is mostly straight, but it is far from a rectangle with a half circle on each end so I'm not sure how range finding would help. Maybe you can explain?

I found the map tool that encloses an irregular shape by connecting many many dots along the perimeter was very helpful.

I suspect the apps that let you walk the boundary would be very helpful as well.