Yep, that’s what I would do as well:
- take POL6, either MV or HV
- keep AT guided VO2max progression
- substitute Threshold progression with Sweet Spot Progression. Interesting post is 180 and it’s followups. Start with whatever level you think is appropriate for you currently but at some point start doing longer and longer 1x intervals (1x60 → 1x180) to improve fatigue resiliency
- fill other days with Z2 guided by LT1 HR
Caveat: haven’t done any multi-day events yet, still working on squeezing longest distance into 12-24h.