There’s a partial answer to your question from Scott Johnston in this thread:
Given that you’re severely aerotically deficient, you ideally want to do aerobic workouts at least 4 times a week.
The other thing to take into consideration is that aerobic work close to strength work can actually negate some of the gains from the strength work. So if you plan to do any double days, make sure you have a few hours between strength and aerobic. There was a whole thread on exactly that topic which I’m still trying to find. If or when I do, I’ll post it here.