It can all be repaired. I, too, found that my car was very rotted. Although I can weld, I felt it was beyond my scope and found a fellow to do the work. I bought the full pans, made in US, that run from toeboard to rear seat back seam and had the entire area replaced. This gave me a new base, including the tranny tunnel. Also replaced was the rocker inners and parts of the internal rocker reinforcements. There was other repairs and now I'm back on track. A lot of $ but I don't plan on getting rid of the car.
69 RS Conv,355,M20,4.10's and I don't worry about stone chips ( yet ).