'63 Fury Convertible Trunk Restoration

Looking for anyone in the know about the brackets I've photo'd. The inside quarters are coated with rubberized or tar-like undercoating and some areas have appreciable surface rusting so scraping off coating to expose the metal. My plan is to apply a rust inhibitor such as "Extend" or similar product I've been researching and then apply a top coat with some insulating properties. Also been exploring best products on this and there are many to be had. I hope to use the coating for the entire trunk deck and interior as well.
My question is the bracketing pictured and if this can be loosened or removed to let me get behind the rail for rust treatment. It appears bolted and not welded to the quarters but if anyone has been through this appreciate any advice. Thanks.

Trying to remember. I have a set of the braces and brackets blasted and detailed.
They are bolted on. I think the ones towards the front are difficult to get to, if at all.
They push against the quarter to keep it stable, has a piece of some type of rigid insulation between them and the quarter.
I do have some extra parts.
I have a ready to paint front lower valance. They are re poping them for $335 + shipping. Mine is $275 shipped.

That push against support you mention makes sense to me and thought it might have some relationship with being a convertible for added body rigidity. Yes there is some padding between the rail and quarter I'd sure like to get behind to treat metal there. As for the front section appears accessible if I take out the rear window regulators; but the area looks pretty clean with the coating solid...no missing chunks of the coating far as I can see. This is a CA car I've had 20 years never seen salt much less much rain since I've had it. All was well hidden behind plastic shrouding and trunk carpeting. I've been stripping car down in prep for repaint.

They are convert, ONLY

In your experience did you move or take these rails out by chance?