If you're talking about just one breast, there's nothing to stuff. There's no cavity. Not that you should do that anyway, unless you want to give thanks for salmonella. I suppose you could butterfly it and create a sort-of roulade, but I wouldn't.

My wife has done pretty well with a single breast by just putting some salt and pepper on the skin, putting it in the oven on a sheet pan, and baking it. I don't know offhand how hot or how long, but I'd guess about 350F for about 90 minutes.

As far as temperature and thermometers, if you leave it in the heat until the center of the breast is done, you're going to end up with an overdone, super-dry turkey. Remember that once you remove it from the heat, the center is going to continue to get warmer for at least five minutes, and probably another five degrees. Also, don't pull the thermometer probe out until after it's rested for five to ten minutes; it will just leave a hole for the juices to be pushed out of by the constricted proteins. The same goes for the useless popup thermometer, if your breast has one; don't remove it until ready to serve, but ignore it otherwise.