this is why it was recommended to me to purchase 1/2 a mercedes floor pan! they just sawed that carcass in half. it was up to me to cut appropriately and weld into place. there were a few other places that required patches, but for the most part, i welded 1 solid, rust free piece in and just did a few patches here and there to take care of the rest

i like por15 + fiberglass but make sure its in non-structural areas! and wear a vapor mask and vent the air out. that stuff is not good, unless you were a paint huffer in your previous teenage years

edit: it looks like your welds could be a little hotter. good that you are tacking, but it looks like you are not pulling or pushing your welds, just tacking. it's effective, but man, you must be getting tired tacking all the time, no?

my setting for the floor plan on my lincoln 120V welder was C + 4. easy to remember