I am retrofitting a tile shower with grab bars. The wall opposite the shower head is about 32" wide. With the backer board, tile, etc. the stud at one end is not reachable for fastener and the other end of the wall has the shower door frame attached which takes up that stud. This leaves only 1 usable stud for fastening. With backer board, tile thickness, etc. the wall is about 1 1/2" thick. Is there any reasonable way to fasten a grab bar other than vertically on the middle stud?