Deve
Here's a dimension for you. I measured from the forward face of the inboard fender bolt hole (the lower one) forward to the centerline of the inboard bolt hole of the middle running board mounting bracket. Dimension was 29 5/8". Measured it on the best side and checked against the other side as well. Got pretty much the same dimension there as well.
You should be able to go from that and locate the front and rear mounting brackets using the dims from the FAM.
Hope that helps.