clearing land for passive solar and gardens - how much?

Apologies if this isn't the right forum/heading for this subject, this was just a best guess.

Here's the situation:
Working with a client who wants to build a house on an 8.5-acre wooded parcel. Catskill mountains, New York, zone 6a, 42 degrees N. The parcel they purchased is second- or third-growth forest with some 100-year-old hardwoods - mostly oak and red maple - pine and hemlock. There are some understory species, like trout lily, that we'd like to preserve. Their budget is limited, and they have no idea what they're doing, so my goal is just to guide them into better decisions. They want to grow food, have a teenager who wants goats or sheep, etc. Tree canopy height on the land is about 60-70 feet, dominated by hardwoods.

Main question is, how much land needs to be cleared for a reasonable amount of passive solar and a moderate garden area? I'm figuring a minimum 100' radius from the south wall, just for the passive solar, but that doesn't fully take into account the angle of early morning light, and doesn't give much room for a garden (figuring they'll want to grow standard US garden veggies and perennials that need 6-8+ hours of sunlight/day; they're interested in cultivating mushrooms etc, but will want some full-sun crops as well). How do y'all calculate this? Do you just take solar pathfinder readings and mark the trees that need to be cut, or is there a formula that works? Thanks for any and all thoughts.

I hear you about guiding the client to better decisions. This sounds like it might be a situation where you need to minimize the impact on the forest. It sounds like this is fairly high-quality regrowth. If that is the case I would try to steer this client away from clearing any more than the bare minimum. Definitely cultivating mushrooms is probably a good choice in this area. In order to maximize the amount of sunlight while minimizing clearing size, I would suggest using strategically placed windows or even mirrors to get sunlight under the canopy.

I understand your client might not go for it, but an oehler-inspired kind of house might be the ideal for this spot, in order to minimize loss of forest.

Solar pathfinder readings are certainly a way to determine which trees must be sacrificed. I like this website: https://www.suncalc.org

Topography is a critical factor here. If the land slopes north, or has a big hill to the south/southeast/southwest, there may be no practical way to get passive solar heating without clearcutting the place. If there is an accessible location with a south slope, it may be easy to do with minimal tree clearing.

The construction style they want is also relevant; timber framing would make good use of trees that need to be cut.

If they do any clearing for passive solar, there will be enough space near the south wall for a good garden. Summer sun will illuminate far more ground than required winter gain for the house would give.

So a general idea of the layout of this parcel is needed before we can give any sort of specificity to recommendations.