hey Chris , I think you could just lend your car to me and send it back home to California ....
I had a similar issue with a recent purchase and the rockers were so full of rocks, dirt, nests from different creatures....
I started by removing all the plugs I could get to. Next (if present)remove the rocker moulding. Then remove the lower bolt the attaches the fender on the very bottom of the car.
OK now whip out a hose or if you have a pressure washer and start in the front hole forcing it out the rear one, when you see the water running clear, switch to the rear and spray it in that hole towards the front. Keep repeating this procedure until it runs clear both ways.
You now can pull the fender a inch or so out at the bottom and use a spray nozzle all upside down, and hit every crevice.
Again keep moving it around until you don't see muddy water or debris coming out.
open up the door get the hose in there and spray past the door hinges as best you can.
What I found is while you don't want water and moisture in these areas, it is worse when the weep holes and provisions for the water to drain are clogged with dirt and scale and nests, and 40 years of crap.
Now once you are confident you got everything out you can bolt your fender back up and put your rocker moulding back on. Then re-install the good rubber plugs or put in some new ones.
Now if you really want to make it bullet proof you can go to Ziebart and have them spray there rubberized material in through the drains and what not, BUT if you are no longer driving it in the snow, dirt, and mud you will probably be fine without it.
I would take some spray paint, or undercoat in a can, and spray the bare metal that was in the pic. (If it was me I would get the mig welder out and fill those rust pin holes in first, followed by a small grinder or dremel in the tight spots to grind and smooth it down. )
This is what has worked for me. I am sure there is more than one way to do it though..
Maybe it would be better after washing the inside ,That you use an air compressure to blow out any left over water that will still be inside.After that I think I would wait a few days before I put the rubber plugs back in. You dont want to seal any moisture inside.Good luck.