Hi Ginge, was looking at your roll bar and suspension mount assembly and had a thought. For those nuts there and also for lower harness mounts would be very comfortable to use special weld nuts. They just need a bit larger hole but are self centering and easy to fixate. Here's a linkey with drawing and dimensional table
http://www.deepri.com/din_specificat...Weld-Nuts.html. I design conveyors every day and we use them a lot. Don't know how available those are over you, but should be.