By the way, I ended up running at a command prompt so I2P would always start and run as a daemon at boot-up time so I don't have to manually start it. Plus I2P is always on as long as my computer's running which should help the network.

Thanks! Who'd have thought it would be that easy?

Typical newbie question: how do I configure I2P as a servive in Linux Mint 18.3 (Ubuntu-based)?