First up was replacing the stainless steel phillips-head screws with hex socket head screws. I could only locate black ones locally so I may order some stainless ones in the future.
Here's how they look installed with the painted washers...
Once again I wound up at Lowe's tonight needing some aluminum roof flashing and some more silicone adhesive.
For 43 cents each, I am going to cut these to fit between the skin panels, where there is a gap at the bottom.
After trimmed up, they will fit the opening. My plan, after priming and painting, is to have the piece be bolted into place from under the frame.
I clamped the pieces together and trimmed them to the right size. After this, I used contact cement to bond them together.
Finally, on to the side vents.
With some large painter's tape, I taped the side vent into the desirable spot...
Then, from inisde, I determined the right spot for the L bracket on the frame. I marked off the spot on the frame ring.
I mixed up some JB Weld and placed a dab on the frame ring then placed the L-Bracket onto it. To reinforce the bond, I added more JB Weld to the top and sides.
Tomorrow we'll have to remove the tape and see how well the JB Weld holds when the side vent is removed. Fingers crossed!