I welded a scab plate to the tub behind the fender extension that is drilled and tapped so they can be removed and replaced as necessary. I also welded the DP corners on and blended with the fender scab plate with a skim coat of filler.
Next time I do one of these I'll use something thinner than 14 GA DP, forming the corner radius was really tough, but at least I won't have to worry about denting them when backing up in the brush. And they give a nice secure mount for the tire carrier. The DP will be shot with black Line-X, and the rest of the tub with Yellow.