Update: I was able to both shed the phantom render files and shrink the project to a reasonable 57mb by combining both suggestions above. Thanks again for those.
But the project still won’t export. When exporting to Compressor, the project gets tantalizingly close to completion before crashing with a EXC_BAD_ACCESS (SIGBUS) error.
I’ve read this can be due to either bad RAM, or a bug in the software.
Unfortunately I can’t open the Apple Hardware Test to check my RAM (nothing happens when I press D on startup), but I did save the crash report, attached.
To anyone who can interpret it, who does it implicate in the crash – the RAM or a bug?