Hi Seth,
I have also been thinking about combining the "Greenhouse in the Snow" design with the lessons learned from the following two books:
* The Forest Garden Greenhouse, by Jerome Osentowski [Central Rocky Mountain Permaculture Institute]
* Year-Round Solar Greenhouse, by Marc Plinke [Ceres Greenhouse Solutions]
I wish I fully understood the similarities and differences between these designs, but I just don't have a mind for building and mechanicals like some people do.
Check out the post by "Ingevald" here:
https://www.ourfigs.com/forum/figs-home/385110-geothermal-heated-greenhouse for a more in-depth commentary.
- Jeff