I dug into it tonight after work. Pulled the trim strip, then had to pull the bottom panel (it is a metal panel about 10 in high that goes around the bottom of the entire trailer)
Now I could see what I needed to. There were a total of 5, yes 5, 3 in screws along the back wall, 4 of which had rusted thru and broken off. They look like 3 in deck screws with the the #2 sq drive head.
I pulled them all out, removed what looked to be spray foam from between the wall and floor framing. Then put in new 3 in exterior construction screws every 6 inches with fender washers under them to help spread the load. I got it pulled back to about 1/8 gap which I need to fill. I'll probably end up backing them off again and putting some foam backer rod in there first then topping it off with spray foam.
I guess they didn't really build them much better in 2007 than they seem to now from what I read.