First off, big thank you to mnemonicmind for writing up those instructions.

Rather than using a full-blown VM, I decided to try using a Docker container as a more lightweight way to install and compile all the necessary bits and pieces. After some tinkering I finally got it working and was able to extract my keys.

I figure my solution might be of use to others, so I wrapped up with some handy shell scripts and shared it all here: https://github.com/c1rrus/bitcoin-wallet-decode

If you've ended up in this thread wanting to extract your keys from a Bitcoin Wallet for Android backup, then my solution might save you a bit of time :-)