Planting mature fruit trees into bad soil in Naussau -- any way to make it work?

I will be planting fruit trees next year in a soil that is very hard with rocks, clay and where it is hard to grow anything.
The person who owns this parcel of land wants mature large trees, the kind you get for $350 at the nursery.

I'm afraid that such mature trees won't adapt well to the soil.

What do you folks recommend?

It sounds like this land owner has more money than knowledge. Mature trees are always a risk to transplant anyway.

It sounds to me like you need to persuade this owner to invest seriously in soil rehabilitation -- according to this article: Improving Clay Soils it appears your basic approach is the same as what all of us permaculture folks advocate anyway: lots of organic matter, and build up the nutrient cycling. As to how to get that on a scale that would help these trees -- does the management team have access to trucks and earth moving machines? Perhaps you should educate this owner about the old farmer's adage: if you have a dollar to spend on your farm, spend 95 cents on the soil and 5 cents on the plants.

I understand why the owner wants mature trees.
Plant the mature trees every 20ft and between then plant regular trees.
He will have his mature trees for 3 years and buy the time they all die the 'regular' ones will have taken over.

Also don't be afraid to buy tons of biochar and also dig swale, and import innoculants and rockdust and woodchip.

You can make him happy and also make the soil/ecology happy.

Thank you!
Why are mature trees so sensitive to transplantation? I think the owner wants large trees because their leaves produce more organics, long term mending strategy. But maybe planting a mix of semi drwarves for immediate fruit production, alongside some variety of trees that produces a lot of leaves might be a good alternate solution?

Can you check if I get these right?
1- clay soil is naturally fertile but the compact structure and water impermeability prevents the roots from breathing.
2- mending clay soil requires a short term and long term strategy
   2a- short term is done by mixing organics with the soil
   2b- long term is done with cover crops (clover?)
3- preventing water logging is important and done by planting trees in burms above surface
4- A swale a trench where the burm part is mixed with organics, and that burm is where planting occurs.
5- A swale allows water to move, a huggel culture does not.
6- water moving is ok with roots, water stagnating causes root rot.

Equipment they have:
a default bobcat skid steer

A hand held 16" gas powered Auger, no backhoe.

The Auger is an absolute nightmare to use in this soil and nearly useless in my experience as digging with shovel ends up being faster even to install posts. The last time I worked on that land, I mixed water thinking that it would soften the soil, instead it turned it into glue.

Logistic:
The default bobcat might be good enough to dig trench for swale building, but mixing organics in so much burm (100 trees worth) will need a clever solution. The first thing that comes to mind is doing a hybrid huggel/swale by digging a trench 2x the width, place logs in one half and push the earth over that half. Any better idea?

I wonder if having them invest in one of these helps.

I've got rocky, heavy clay here. Clay has quite a few benefits, but it must be tempered with a LARGE amount of soil amendments. When a tree first goes in, I dig a massive hole. Three or four times the size of the root ball, leaving a big "cushion" between the bottom of the ball and where the clay starts. Then, I completely blanket the clay soil with wood chips, pine tree mulch (anything highly acidic), and compost. The whole yard, or at least as large a portion as possible. Over time, as you add layers of organic matter, they break down and work into the clay. It is incredibly hot and arid where I live, so I add about six inches or so of mulch right up to the trunks of my trees.

That being said, I've never planted a very large tree. Biggest ones I bring home come in five gallon pots.