roymunson,
I used telephone poles on a 5x30 fixed walkway and 16x24 dock on a 2.7 acre pond. The decking that I went with is maintenance free. It doesn’t splinter, get hot, need staining and is made in the USA. You can see it here.
Btw I’m glad that I didn’t build it any smaller.

https://imgur.com/gallery/aERJTEL