It's been a long time, maybe 7 years, since I installed the 935 and don't remember having to drill any holes so either the one they provided lined up for me or I used the drill press and don't remember having to do it. If I did have to drill, I would have followed the instructions and only drilled through one wall only. I went out and checked it just now and none of the bolts go all the way through. My suggestion is assume the engineers that designed it knew what they were doing and follow their instructions.
Edit: I went out again and checked the size of the set screws that came with it and they mic right at 0.3000" diameter. The instructions call for a 3/8" bit (0.3750") so I agree that might be a bit on the slack side of a snug fit. You can always start out with a 5/16" bit (0.3125") and if it won't go together gradually work your way up to 3/8".