Rusty bed floor replacement

[jets4343]

I have a '69 F100 short bed that I need to repair/replace the bed floor. I have one big hole in the front and it looks like the bed has hauled something heavy. It is bowed down real bad. I'm replacing the front panel and wheel wells. The exterior is in great shape and hate to buy a bed unless I can find one cheap. Which repair patches do you guys suggest? Found some on ebay that are 18 gauge and 16"x48". This is the first time I have had to do the bed floor. I have done years worth of body work and welding but would like some ideas on what to do to this bed. Thanks!!!