If it were me, I would focus all of my immediate efforts into Hardy Chicago. The Bo Ji Hong looks like California Brown Turkey, which was more trouble than it was worth for me. It might be useful for the breba crop, but those nearly all drop here so it still seems like a long shot.
Figs with light interiors don’t have mass appeal like Hardy Chicago. You could trial Florea, it probably would be more productive for you but everyone I have surveyed prefers the taste of Hardy Chicago.
What I have been doing for winter is fairly minimal, you would probably need to do something more like @DCinFLX. Low Tunnel Winter Protection (Figs, etc.)
I feel like a climate battery/geothermal greenhouse is a huge improvement over both a high tunnel or conventionally heated greenhouse. In the mountains though, I think that much excavation could be a problem. You may also need to dig down in zone 5, similar to the original concept in Nebraska.
It would be a very big investment compared to low tunnels. I really don’t know enough to say whether it would be worth it. You could give your trees a little bit of a head start in a low tunnel, and could simply cover with frost blanket in the fall for season extension to get some of the same benefits at a much lower cost/larger scale.