Frame Parts

I am trying to get some information on repairing some parts of the frame on my 93 k1500. The spare tire carrier has all but dropped off. Well its pretty rusty anyway. I was thinking of just replacing that with some tube steel, any ideas there? I think that it should be stronger after that. Also the frame rails in that same area closer to the bumper look kind of bad. Should I just get the rust off, and put a good primer and paint it? OR cutt of the parts of the rail that are bad and replace them? There are no holes there and I have had some weight on it, but I am going to be towing some trailers mainly not long distances but could have up to a couple ton in them. So what do you guys think??