I have the tree. First I spray it with Starsan, then to sanitize the bottles, I take a measuring cup of starsan like the one below.
Pour some starsan in, then with the bottle horizontal, rotate it so the solution coats the entire inside. Then pour it back in the cup. Dip the mouth of the bottle in the cup of starsan and then place on the tree. Repeat.
This method works very well with very little foam and you can sanitize a ton of bottles with about 12 ounces of solution.