Interior panel corrosion

I have a 110 CSW that I am doing some work on. Generally it is in excellent condition and most of what I am doing to it is cosmetic. I have just removed the carpet in the rear compartment prior to fitting chequer plating and found a lot of aluminium corrosion/etching. This doesn't appear to be the usual 'galvanic' reaction but something eating into the aluminium causing severe pitting and forming a white powder liek substance. The carpet was very wet when removed, this had been masked by a chequer plate panel being laid (but not fixed in place) over the carpet.
I think this vehicle was used to tow boats so could this be salt water corrosion? Whatever it is can anyone advise how to prepare and treat it to stop it getting worse?
Many thanks
Andy

That is typically aluminium corrosion, I have got it on my 90 where road salt has got to it, I know that aluminium in salt water will go that white way, but I think that is standard of any aluminium corrosion salt or not.

Let it all dry out, then give it a grind/sand until ckean metal.

Also they may have had the back end in the water, in which case I would check the chassis and get some waxoil into the box section aswell incase its been filled with salt water.

Its a very hard thing to get rid of is Aly corrosion. Is there no option to fit a new panel ya think or are you not that bothered. Winter is on its way and its not going to get any better at all.