I am assuming our young stovebolter is refering to what is commonly called soft soldering. Whereas brazing would be called hard soldering. Sheet metal can be soldered without any problems. The thing is soldering is mainly used for sealing. To the best of my limited knowledge it has never been used for structural purposes in the automotive industry. Although there has probably been someone who has built a car body by soldering the panels together.
The newer cars have a lot of panels that are attached with glue. This seems to work very well for patch panels. The question I think you need to answer is this. Are the repairs structural or cosmetic. If it is structural, and remember the floor is pretty much all structural, then welding is what is required to maintain the support for the rest of the cab.
If there were just a few small holes that you wanted to seal in the floor, soldering or glueing would be OK.
You will soon be in High School. Most High Schools have some form of vocational classes. Visit your local High School and see if they have an auto shop or metal shop. With the right instructor, this can be a great resourse.
Do some searches online for auto body sites, you will find a wealth of information about repairing sheet metal.
Good luck on your project. I did not get my first Advance Design truck until I was 17, that was 40 years ago. I have loved the design ever since. Have fun, look around your community for someone else that is restoring an old car or truck and partner with them. They can teach you alot.
