When I ran for 2 players, I left it as-is, and played it RAW (Rules as Written) .
The players were fine with that!
What you will note is that Obs tend to be a bit lower, as you’re only trying to Dungeoneer (say) 2 people, rather than 6.
There’s other bits and pieces, such as fewer light sources are needed to cover them, and loot goes further!
One thing my 3-player group does is set up caches of supplies (and loot), so that they’ve got concealed camps with supplies already stashed.
I, personally, don’t think you need to alter anything, and would play it straight.
The players just have to be smart about stuff!
Don’t forget the Good Idea rule, which is such a boon to clever adventurers / players!