Hey Taylor
Go to the home page and look under Crappie Cover, Lake Structure ect, plenty of great advice over there. The only problem I see with Christmas trees is they don't last very long. If ya got any neighbors with bamboo that would make an excellent material to use. Just look through that cover thread, lots of ideas in there. For depth I would try setting the cover in 10 fow first and then go from there. One of the hardest parts of setting cover is getting it to sink, remember ships were make from wood for a reason.

I'm very familiar with the water in which your fishing. We used to fish there back in the late 70's and 80's before the community took over the property.