Here is the method I use (last para). The links have other methods. Those 2 links have a lot of info on the how to do.

That is a Ray Scott method adaptation. Good job !

Here is a concept to think about. Drive a post ( PVC or metal or hard wood 2in. dia. )into the pond bottom in deep water (12 + feet) so the post extends 2 feet above the full pool level. Make your structure items so they will attach to a 4in. pvc collar or metal ring and balance them side to side. Tie trot line rope to the collar or top of the structure so the rope will run up the post. Put the collar over the post and lower it to the depth you want (seasonal) and tie it off to the post. Raise it up or down as you like and you will always know where it is because the post is there. Later raise the structure to the surface add some fresh wood branches or whatever and lower it back. You can even stack them and have structure at different levels at the same time. Get creative. One of my adaptations of the Ray Scott idea.

Here is another. Same post method but no collar. Take xmas trees and remove from 10 to 50 % of the branches and tie small trot line string to the top or middle or bottom to the tree depending on how you want them to hang from the post. Think about what you want first. Then tie them in sequence to the post so the string runs up the post. Example - in 12 ft of water have the first tree ( 50% branches on a 6 ft tree) tied with the line 12 in down from the top of the tree with a 6 ft string and tie it off to the post 2in below water level. The tree will water log and sink to a standing position 1 ft off the bottom covering the 11 to 6 ft depths. Next take a couple trees ( 6ft 60 % branches) and tie them in the middle by weight with a 5 ft string and tie them to the post 1in underwater. They will sink and hang in a horizontal position at 4 to 6 ft deep. Then take a fat short xmas tree ( 4 ft 70 % branches) and tie the string to the bottom of the tree with a 1 ft string and tie it to the post at water level . It will sink bottom up from 5 to 1 ft . Thinner standing cover from 11 to 6 ft for predators with cover over them ( shade) at 4-6 ft not so thick horizontal cover for intermediate sized bait fish followed by thicker cover near surface for small bait fish. Think it out and design what you think best.