Would it be safe to assume that in an aluminum PU Truck Too Box, tools will rust if not protected by plastic boxes/ wraps, etc?
What type of tools? I wouldn't lay wrenches or sockets in there without putting something down on the bottom first. If the box is good and weatherproof you could just cut some heavy cardboard out and lay in there. In my old tool box, I cut up a super cheap roll up bed-liner the was 1/16" rubber, that worked well.
2014 Aerolite 213 RBSL
2016 Chevrolet Colorado
Outside of normal condensation I don't see why you would have a problem. I use the Weather Guard boxes and have never had a problem. Some of my boxes are pushing 20 years old and are still in daily use. They outlast the trucks. We do put a rubber mat in the bottom, IIRC it is the stuff they sell at Tractor Supply, it is about 1/2" thick, cut it to fit. Main reason we use it because the guys like to throw things like axes and mattocks in there.
__________________ There is madness to my methods
2015 Coleman CM16FBS(traded) 2016 Concord 300DS
2015 Ford Fusion Hybrid following along