I am doing a basement project and trying to keep wood/organic products out of the wall to prevent potential wood rot or mold. There are metal studs in place, but these are not good for mounting trim work or cabinets. I am curious if composite decking, mounted horizontally between the studs, would be effective as a way to mount cabinets and trim once the drywall has been installed? Is there any better technique?
There is no reason wood shouldn't suffice. That is the way most basements are built, mold would only be an issue if the is bad drainage and water buildup. But even without that you might just use a dehumidifier to reduce dampness in the basement.
If we are framing a basement that can get water we use pressure treated lumber. All of the problems that you describe are of almost not chance with PT wood. Not really sure what you are going with the actual wall though because that will mold first by far if drywall.
You should use backing plate for metal studs, but they could be difficult to find for diyer. Check clarkdietriech website for details:
You might also order similar thing from custom sheet metal shop.