Forever structure is nice, but there is some value in natural cover too.
Cedar trees that pond owners clear from their fields are a popular item. They start out as very dense cover for the smallest baitfish. After a few years of decay, they have lost all of the small twigs and are great cover for BG. In their final years as mostly just a main trunk, they are great "ambush" cover for the LMB to utilize.
If you don't have cedars that people around the lake clear, you can almost always get Christmas trees for free at the local recycler after New Years.
Almost any cut trees will make good cover, just make sure you do NOT put in freshly cut oak branches or stumps. (Some people have had fish kills due to oak tannins, other people have had zero problems.)
I would definitely tend to use any wood-based structure in the areas where the more experienced fisherman will be fishing. I like your usage of treble-hook resistant plastic pipe for structure. I would also follow Theo's advice and do some of your plastic pipe structures in places that are easy to access for small children to fish.
