I don't recall seeing anyone on here with a build doing that, However I also have seen it done on several trucks. I've seen it done Two ways: (1) Like your describing, plating the inside & switching the springs. (2) Using the existing holes & notching out the bottom lip of the frame so the opposite side spring hangers can slide up against the INSIDE of the original framerail & simply bolting them back on. As much as I'm not a real fan of chopping up a frame...I think if your going to do one of the Two, it has merit since the springs are "out of the way", but still as wide as possible & would be a no brainer to get back in the proper location. Likely a guy would be doing a flip at the same time so the plating is probably going on anyway, but also, if your going to chop a big notch above the axle...whats a couple more small ones on the bottom?
How big of a tire are you wanting to put on your truck? You can get a pretty wide tire in there (14" or so) without moving the springs inboard the frame. Lorne