Smoothing out the inside of bed..what's best?

I am planning on smoothing out the inside of my bed with 18 gauge sheetmetal. I was planning on removing the whole floor and sides and then building a frame that will support the new sheetmetal. I also considered simply building the new bed floor/sides by putting the new sheetmetal over the existing floor and sides(so there would be no need to build a frame). I have not bodydropped the bed either, but i just wanted to hear some more opinions on this...thanks....