Its easiest to take the whole enchalada off at once. Leave the plastic fascia attached to the bumper and take them off together. Once you get em off the truck you can separate them as the bolts will be easier to get to. You should then be able to bolt your new bumper to the tow-hook mounts...take final dimensions...fab any pieces you need...weld them in place. Once you get the bumper how you like it...you can work on a new fascia panel or try to modify the plastic one to fit.
It requires a bunch of on-off-on-off-on-off...repeat as many times as it takes. Be patient...eventually you can pull it all off, grind it smooth, powder-coat it, and re-install for the final time. Looks great so far. Update with some pics when you get it mounted.
