Having a party of "clones" is a really fun way to set up a solo scenario! I like it. Good use of the constraints, feels inspired.
Bookkeeping suggestion: It may be easier to track "time to QWD explosion", rather than hours spent and the time limit, both of which can change. Basically, starting the count from 20 and counting down when time is spent or when the limit moves up. (Sounds like a task for the d20!) But it's a good system. Hard to say how hard making it out in time is, seems like time is plentiful? But can't really say without playing or computing. It still adds a tension, I like it.
Using the checkboxes is nice bit of
But feels like a solid one shot!