@rapidursa
Back when the game came out I was also mostly a solo. I have recently realized that I have preferred to not play without others... So I've been engaging in the old ways again!
Most of the time, I'm in it for commendation hunting. Fishing solo can be one of the most relaxing experiences there is, and it's also something I haven't bothered to finish. I highly recommend fishing for small time periods, because you can pick a zone, gather a bit of bait and sail to a seapost to live out that time. If you are sure you won't run out of bait, it can be good to scuttle your ship to keep people from coming your way.
When I'm in it for gold, I like to voyage in the Devil's Roar. It's just me vs. the world, and I feel good when I sell loot after making it through the challenge. When the reputation caps were increased, I got the main 3 from 55-75 from solo slooping in the Devil's Roar. (This kind of sailing might take too long)
I don't like taking on events as a solo, because I'm always wary of attackers. When I needed skeleton ship sinks for Legend of the Sea of Thieves I did a lot of solo skeleton fleets, though. I'd only do events that other people don't like to go to often, like a skeleton fort or fleet. If you're willing to let go of the gold, doing a fleet in an hour and quitting without selling might be a good idea.
When I'm bored or waiting for my crew to get on the game, I like to sneak around on servers and do something funny to other crews or fight. Sometimes I just join open crew Arena and see what happens.
When I'm really bored I join open crews in Adventure.