I play solo, and its definitely a 'hard mode' but there's some ways to make it work. The main thing is to give yourself two archetypes. You take the age and ability scores of one, one service history from both, and take all of the skills from both (that your crew quality allows). Duplicate skills take the higher skill level +1. You also start with 1 Glory to make up for the lack of other player's bumps. There's some small niche problems that may arise from playing solo, such as not having the required workers to efficiently build bases at the facility level, so you can either just pretend you have 4 crewmembers when needed, or roll with the punches like I do- which while they tend to make the game harder, you go down avenues not previously thought of. Like in my current game I'm trying to build my first base on the venus aerostat, but since I don't have 4 workers, I'll need emancipated robots since they count as workers. But that requires me to not only emancipate robots- which is a whole game changer- it also encourages me to spec into robots earlier on, as this is literally year 1 of the game., and also get the infrastructure to print them. The whole process takes much longer than a simple Industrialization operation, but its a unique experience that I think is worth the extra time.
I plan to write out post-year comments for each year along with any relevant pictures :) My aim is to go for as long as the system allows (including A Lot Of Zeroes), although I'm not exactly fast due to still trying to learn how to play the game. I've spent the past week trying to learn base building and I'm still not entirely knowledgeable on it lol. It does help that I'm an avid fan of High Frontier though, cause that's a whole ruleset I don't have to learn since I already know it.