My first thought is it's really hard, but maybe it's not. I "only" lose 40% of my momentum if I have 1 person instead of 3, I have better draw consistency, I don't have to worry about cards that are unplayable, and only one person has to avoid damage. The only fight that cares about my turns taken is the first fight anyway.
I'm pretty sure it'll still be harder than 2-3 heroes because having extra momentum, teamwork attacks, and more options in general is nice.
store.steampowered.com/app/23...