A small STALKER problem

The game likes to clean up the world at some times, I think during zone changes or some travel. By clean up I mean remove corpses and dropped items, basically anything that isn't in a box or inventory. Well, I need the canister of poison gas from the locked box in the car on the ruined bridge between the ranger station and the waste treatment plant. Slight problem: I found it long before I needed it, thanks to my tendency to explore, but I lacked the capacity to carry it (I needed space for my worthless broken weapons), so I dropped it. Somehow I didn't get around to going back for it until the world had been wiped a few times.

At this point I only see a few options.

I could use the console to spawn it, but none of the commands I've found seem to work.

I could edit the inventory of traders to cause them to sell it. This I don't know how to do, but of course with what I could scrape together from searching, I did managed to make the game crash on startup. Fortunately I had the good sense to have a backup copy of the file I changed. I'm not even sure it was the right one.

I could edit a save file, but they are a completely unintelligible mess that no one seems to know how to work with.

The second option has the added problem that of the advice I've found, it all seems geared toward people who install it normally, rather than it being from Steam, which seems to alter the file structure slightly, and maybe more than that, making it much harder to find what I need.

It's a long shot, but if anyone has any suggestions, beside skipping the mission, I'd be very grateful.