These I think I can slip a little sheet metal behind.
weld a patch....imo
Weld it up and fix it once and for all.
Amen!
unless you like ghetto-rigging,I wouln't attempt to use anything but a new patch and a welder
thems big holes..lol I'd make sure you cut or grind all of that out. Then I'd either weld in a patch or use something like liquid nails to hold it in place. Then you can use a skim coat of filler. I would not start smearing filler over those areas, they need some more work before you start.