what's in the wall?
 

the Dometic awning bracket lag screws mounted upward from the bottom edge of our towlite 22t (2008) are rusted, and the base material of the first 3 inches into the bottom of the wall has decayed and fallen out in wood like shreds.
Is it wood along the bottom of the outside wall of the top?
How is this wall built? Can a filler material like PlasticWood insert and fill this void to take a new screw?

I suspect it IS wood, but I have not taken mine apart to confirm this. I would not trust PlasticWood but a high strength epoxy putty would probably work fine. You'd need to pilot drill the hole before inserting the new lag screw.

Bondo makes a wood repair compound that may work well too.

- Jack

What's in the wall?
 

Please post some pictures so we can better help you.

Here are photos of the location...
 

Sam:
Thanks for the interest...Attachment 4511

Attachment 4512

Attachment 4513

Attachment 4514

In my 2008 I had a similar problem. I had previously had all the leaks fixed at Midget's and Joel informed me to pull the edge trim and let the interior laminate dry real good for a week or so then seal it up again, but do not caulk the trim where it goes underneath (where it is screwed into the top), that way any moisture has a way to escape, water can't do much there anyway because it would need to travel upward and as long as there is a way for it to drain it shouldn't be an issue.

When I pulled the trim, it was soaked inside...even though all the leak paths were fixed. The structure is square tubing around the entire perimeter with plywood mounted 'inside' the tube frame. The screws and bolts mount into the tubing. I did the opposite side of where you have the problem, and before winter I am going to pull the trim on the side with the awing and let it dry out real good then seal it up again.

hope this helps

One other thing...any fastener I remove I replace with stainless. No more rusty bolts.

Yes, indeed, a wood filled channel!
 

Thanks for that insight!
the rotted screw hole voids had to be woodfill epoxy injected from below the bottom edge. I used Minwax wood filler and fillable caulking gun tube, got just enough pressure to push up the fresh filler into the void. Then pushed petroleum jelly coated screw (3 in.X 1/4 in. lag hex)into the setting epoxy, just short of fully inserted. After full cure, torqued the screw in gently.
Now we have to keep that channel dry!;)