I am no weldor but, I do have a welder that I used to do my floors with some success. I practiced on some scrap sheet metal and on some old wrought iron just to see if I could create a good bead and stick stuff together. Clean the metal well. And make sure the metal on your truck you are welding is clean and full thickness (not ground thin or rusted thin) or you will make more holes.
If you have floor panels to do do them first for practice. no one will see them anyway.
Let us know how it goes.
