double layer hood front edge

I am working on the front edge of a mazda protege hood to patch rust holes in the top surface. I was considering welding in a patch but the problem is I don't have access to the backside of the surface because there is a second layer to the hood about an inch inside. I can't clean up or pain the inside of the hood metal before I weld.

Any suggestions?

Have you priced-out a new/used hood?

It may be easier just to replace it than to weld thin sheet steel and finish the curved edge.

If you must weld, imho just weld in the patch then use a rust-proofing compound in a spray can... the kind with the tiny spray tube on the end.

Chances are, you can work the tube in through the seams, or drill tiny holes on the underside, to spray rust proofing compund on the bare or rusty metal.