If it’s flat out crashing and doesn’t seem to have any information in the log file you might also want to try running Duplicati from the command line with the --verbose parameter and see if you can get more detail from the console window (just as a test, of course).
I don’t know of one either, but I sure like your idea. I thought there was a similar suggesting already made but I’m not finding it right now. How does this look to you?