I may be missing something here, but why not take a suitable model kit and convert it into a wreck of your own? Depending on how trashed it is you could probably eke multiple wrecks out of a single kit, maybe doing one as a recent crash, another as a long-abandoned wreck that's partially overgrown, and maybe even some kind of post-apoc shanty hut out of the leftovers.
I grew up demolishing model kits, so maybe it's just me though.