I was planning to use Handbrake to generate a file that I would feed to VP20. You are suggesting that HB can be used as a VP20 plug-in?
Sorry, Handbrake is a separate, open-source GPL application with no connection whatsoever to Vegas, which is a commercial application. We use it so much, it is more like a country cousin.
You should make a Constant Frame Rate file in Handbrake for trouble-free import.
Others here are also recommending Shutter Encoder, once again an entirely separate encoding application. IDK if it rips straight from disk. Google is your friend 😏