Some things to keep in mind when adding structure.
Taller items, that go from the bottom to fairly close to the top give fish choices of depth/temperature. Vertical height is desirable.
If you are not going to use aeration, any structure below the thermocline when the water stratifies (and becomes low in oxygen) in the summer will be used little to none by the fish (but will be used in the winter of after pond turn over). With adequate aeration and breaking up the stratification this is not as much of an issue. A lot of your forage fish are going to be in shallow water a lot of the year.
Small structure (less than a foot tall) placed on the bottom is likely to get covered with muck and or FA and becoming of little value in a few years.
Just some thoughts. Lots of info and what other people have done in the structure archives.
Structure cover archives In my way of thinking, the Christmas tree you have laying horizontally would be much better placed vertically. Base end in bucket with a sack of quickcreet and some water to keep it from floating and in the vertical position. Placed at a depth where the top of the tree will be about a foot under water at full pool, or a little deeper if needed for boats. But that's just me. I could be wrong.
