Rocker Question

My passenger side rocker is bashed up and pretty thoroughly rusted out, and my driver's side rocker is on its way. What I was thinking of doing was to just cut out between the top edge (where the door seals to) and the trim tab on the bottom, then installing Rusty's rocker guards to hide the hole where the rockers were. This way I still have the trim tab to mount the rocker guards to and something for the bottom of the door to seal on. Does anyone reccoment against doing this? It is way cheaper to use my angle grinder and buy a set of rocker guards than to have them replaced by the body shop I go to for nealy $1000. Thanks for your help guys.

search, this has been covered a lot.
what you do it cut the rocker out and replace with square tube.