I did a week alone with my kids at 1, 3, 5 and again at 3, 5, 7. They were just parts of longer trips (family coming for the second week, or my husband not getting all the vacation time from work and coming later). My middle kid has sensory issues/behavioral struggles, so it was like having two toddlers both times.
Honestly, those are some of my best vacation memories. I think it's incredibly doable, especially with another experience mom!