Bathroom sconce mounting issues

I hated the old sconce installed by the last owner, so I decided to remove the old bathroom sconce and mount a new one. In the process of doing so I ran into two issues. (1) After removing the old sconce, I noticed the porcelain wall tiles were not cut to a rectangular opening matching the size of the box behind, in addition, behind is a metal handy box. If it were me for a sconce I would mount a 4"x4" square box with a round mud ring...but OK. I could work with it and got everything wired, mounting the fixture bar was a bit tricky as I need to use extra long screws and thread in a pair of nuts to better secure the fixture mounting bar. Here are some pictures of what I am talking about. Image: http://i173.photobucket.com/albums/w67/143house/11th/IMAG2845_zpsalvikzwl.jpg Image: http://i173.photobucket.com/albums/w67/143house/11th/IMAG2846_zpslxtl8bfc.jpg