Raising bed floor???

I have been in the process of 4 linking my truck for like 3 years now , and am mounting everything under the bed in a semi-uncluttered arrangement. I did this, so I could raise the bed floor, and have full floor, rather than the hole for the axle and notch.

I have never raised a bed floor before, and want to know the simplest mehtod, that will yield the cleanes results. Any one have any progress pics from doing theirs? Worse comes to worse, I will figure it out. Some pics and maybe a brief description would be great though.

P.S. the truck will not be bodydropped, just the bed floor.