Have you tried this in Vt (8000 HDD)?
The last super-insulated modified Larsen Truss house I built is in Warren (8500 HDD), on a shallow, frost-protected foundation. While I have no data to prove that it's freezeproof, I would be willing to bet that it is. It's only moderately passive solar (8.27% of floor area in south glazing), so while it gets about 37% of its heat load from the sun, there's not a great deal of nighttime heat loss (even though the windows are only double-glazed lowEČ).
I am curious if your MA house had optimal solar orientation.
Yes, every superinsulated house I've built has faced due solar south, with little-to-no south shading coefficient, to maximize the solar contribution (37%-55%).