I did add a plank,I didn't feel comfortable with just the 2 screws holding 100 plus pounds.
The plank is iron wood and noched on the back side so the mounts drop through and still sit flush.
After all was notched and drilled, I cut it long enough to hit a few studs.
The screws are 3" and there 3 in each stud.
The plank is 3/4" thick
This made it easy to center the light.
The studs were no where close to where I had to mount, and a toggel or somthing else would have failed.
Could you imagine the wife comming home to 180 gals on the floor?
Kedd