Another brook trout lover! Congrats.
I have a simple floating pool or pond thermometer that I use for surface temperature and for depth temp measurement. I attach a sinker to the device to pull it to the bottom, and have a line attached which I use to retrieve the thermometer.
Are you adding forage fish or other species of catchable fish? If not, I'd say skip the x-mas trees. Trout typically don't hang out in cover; they nearly continuously cruise. Sure, in a stream environment, they'll hang in front of and behind rocks an logs, etc. But in your still water environment, I believe they'd swim in the open. With no brush on the bottom, you'll be able to fish without fear of snagging, too.
Aquatic plants could benefit your brookies by providing food and cover for insect larvae and other edible critters.
Good luck with this project. Please keep this thread going. There are only a few of us posting about trout in our ponds. wmbuffetjr has brookies; all I've got are lowly tiger trout and now rainbows again. I added 23 'bows a couple of days ago, ranging from 12" to 16".
