Installing a ceiling fan box
In a singlewide trailer (read: No accessible attic and rafters only every 3-4 feet).
I cut a hole where I wanted the fan, which is fortunately right next to one of the rafters.
The first hole ended up not being big enough. See in this photo the 1×4 that has been screwed to the rafter.
I kept screwing 1x4s to the one attached to the rafter until the end result was this.
That gave me something solid to attach the fan box to:
Now all the drywall is put back up, the only repairs left are to fill the gaps with drywall compound and then respray the ceiling texture to match before installing the fan.