I’m a registered user of LotW, but not an ARRL member. Pretty sure they sent it to all registered users.

Yes, the story engine is the core system. It’s primarily what I used for my solo game, as Traveller has enough other systems to fill in the world running. But I think the character engine might be simpler than using something like the Traveller 5 personals system if you truly need some randomness to how NPCs will react.

I’m going to suggest the Motif system, as it has Story, Character, and World emulators that might make it easier to run.

https://www.drivethrurpg.com/en/publisher/7970/thought-punks/category/38729/motif-framework

I have used this system for a solo game of Traveller and it worked quite well.