Working through the channel, measure the distance between the joists and cut a 2x4 to this length. Attach a fan-rated outlet box to the midpoint of the 2x4 where you want the fixture to be. Attach a joist hanger to each end of the 2x4, keeping them flush, not protruding past the end of the wood. Butting the 2x4 against a flat surface while assembling can help to keep the bracket set properly. Insert the support assembly between the joists and set it so the outlet box is flush with the ceiling surface.
Press a small board against the bottom of the outlet box to hold it flush with the ceiling while attaching the support assembly to the joists. Working through the channel, drive deck screws or nails through the holes in the metal hangers and into the joist. Use four screws on both ends of the support, two on each side of the hangers.
Another switch you may find in your home is a 4-way switch. These have four terminal screws and a fifth green one for a ground wire. Four-way switches are used between two 3-way switches to control lights from 3 or more locations. This can be handy if you have a large room with several entrances requiring light control from multiple locations.
Try to remove the wallboard cleanly so it can be reattached when you’re done. The baseboard can be reinstalled without replacing the wallboard, but this will create easy access for pest such as rodents, as well as drafts from cold air during the winter.