These are the downtime rules I’ve been using in my West Marches-ish troupe-play campaign. There’s a lot already covered by the core rules; this starts from there and codifies or explains some other common situations.
Everything covered by these rules is long-term, measured in days or weeks and not moments. We use these rules between sessions, but they can work for any downtime. The PCs are all based out of one steading, so there’s some incentive towards steading-building, but these rules would work fine if you’re moving around; that would change the incentive towards stopping in nicer places. And we completely ignore upkeep costs, but room and board prices can be found in the core rules if you care to use them.