Basic week structure:
Rest, VO2, 2x achievable Endurance, Threshold, 2x productive/stretch Endurance
I’d like to have some maximum effort in there. I’m too small to be a sprinter, but believe my short stompers contain a bit of a kick that would be silly to ignore.
It’s tempting to swap Sprint workouts in for VO2 or Threshold because those kind of hurt 
but i guess that’s what they’re supposed to do.
Where would you strategically place them?
1st achievable workout of the week, to have one more easy/low&slow day before the evil threshold thing comes to kick your butt? Double up on the long sunday ride (before/after?) for the following full recovery day? Just go by the numbers, add it to whatever day says it’s the least TSS?
I’m following a similar structure and add them the day after my VO2Max workout on Tuesdays. Mainly for the reason that on Wednesday, I usually join an easy group ride, but in the end some guys like to sprint. So I’m not only getting the training effect, I’m also learning to sprint from a bunch. I do take Fridays off however to ensure im fully recovered for my threshold workout on saturday. Purely based on my gut feeling I would advice you to do the same: Add some sprints ahead of your full day off at the end of your Z2 ride on Sunday.
How about moving achievable endurance after the rest day (and thus before the vo2) and adding sprints to it?
For me, this order does not take anything away from a hard session the next day, especially if the sprints are 10ish sec and about 5-6 reps. If anything, legs are more awake than after a rest day.
Why not just double up on either your VO2 or Threshold days?
just rotate the schedule a bit anyways, change things up. take a vo2 out one week and hit the sprints!