Yes its always possible, but welding thin metal properly in situ is time consuming and difficult, so its a usually question of whether its economic - which we can't guess without seeing it.
That corrosion is shocking it must have been driven somewhere saltly or not washed off after driven on gritted road. I would be heart broken if my motorhome was like that. That would have to be cut out and plate welded over. Good luck with repaires robin