It hasn't been especially difficult but I think I've got a huge advantage this time in that I'm writing a premade campaign guide for a TTRPG rather than prose fiction. When I'm writing prose I definitely struggle with how much information to include and how to fit it in so it feels natural and doesn't mess up the pacing.
With writing this campaign, I know from the outset that the players are going to miss huge swaths of the content. But the upside is that because they're the ones driving the plot and deciding what to focus on, I'm free to provide as much information as I feel would be useful to the GM and if the players want to engage with it, they will (sort of like side quests and optional audio logs in video games).
I'm definitely a worldbuilding-first writer and I love the fiddley little details that make a place work so this has been an absolute blast. I keep the 'box text' narration stuff short and descriptive but I provide all kinds of information so if the GM has to play an expert on something like a farmer or deconstruction worker, or environmental restoration tech, they'll hopefully have enough to sound like an expert.
The other advantage I have is that the plot (a quest to find thousands of tons of illegally dumped industrial waste in rural New Hampshire) aligns well with my goals.
Basically I wanted to write out how I think rural New England might look in a solarpunk future (a lot like a modernized version of how it did a hundred years ago) and to introduce some practices like ice harvest, spring houses, etc that predate modern tech but align well with solarpunk ideals. I wanted to write some more grounded solarpunk with a lot of emphasis on reuse and salvage. And I wanted to talk about watersheds, groundwater, and how pollution moves through them, and various practices used to remediate different contaminats.
I stocked the game with locations and characters that address one or more of those themes, in various ways. The players' search for the waste is almost bound to bring them through a bunch of these places and to start conversations thatdevelop on those themes.
I hope some of this is useful, I think this is the biggest fiction project I've worked on, and I'm surprised to find that it's going much better logistically than previous attempts at writing prose novels. I think the worldbuilding-heavy structure and lack of a single set plotline just worked really well with how I write.