I installed the same fence you mentioned 2 years ago. Here is what I did:
1. I placed the post into the hole
2. poured dry concrete mix around the post
3. used a safety cone as a funnel to pour dry concrete mix inside the post to just below where the bottom rail goes into the post.
4...
Cut a hole in the pegboard for the outlet, put an extension on the outlet box to bring it flush with the surface of the pegboard. For the water connections, you can cut a hole as well and it trim it out, maybe?