I have not heard anyone mention a sub-soiler. It is like a strong piece of steel that cuts a slit effectively eliminating the compaction along it. This is pretty much the same as a keyline plow. In my opinion it is the best way to get your soil in good condition and pretty fast too. It works even better if you can inject compost tea and soil improving plants at the same time the lines are being ripped. This doesn't till the soil. Contrary to popular belief, that soil should be built from the top up, this does the opposite an is much less dependent on inputs to work.
Mark Shepard talks about this and after 2 yeas your soil will be radically different and much deeper. I was just at Marks farm this summer and I could easily stick my hand down a foot at least into very good loose friable, well airated, and rich organic matter soil in one of the subsoiler slits.
If you do this it will open up the clay to be broken down more easily by insect and roots will colonize further down looking for moisture and nutrients. Every year you will have some root decay and this will continue to improve the soil deeper down until finally the clay no longer resembles clay. It wll be rich and dark soil full of life. If you can do this the first two years and get soil improving crops as well as forage crops planted you can begin running animals in there. Hogs would be good because they will prepare the soil for you and after they leave the paddock you can begin seeding your food forest. I would recommend sowing some wild root stocks from seed that you can simply graft on to unless you want dwarfing root stocks. If you can grow your own root stock though in very tough conditions you know it will survive almost anything. After that you can graze cattle in a silviculture system managing as a savanah. I recommend planting trees that you can trim for the cattle. Quick growing like poplar. And if you so choose continue your succession into a complete closed canopy. This all can be done hand In hand with establishing your food forest. The first two years of subsoiling will do wonders for your soil and the animals will further improve that as long as you manage a good rotational grazing plan. And it will also be profitable why your food Forrest is coming up. If there are certain plants that you don't want your animals to touch just don't include them access to that area. You can have islands within the system where you develop the human aspect of your Forrest with medicinals and other edible beside the trees. The subsoiling will be enough to improve those sites, although I do recomend having animals on the entire area so all can derive equal benefits from animal fertilizer. Also Swales are a must and pocket ponds unless your site is historically swampy. You dont want it all to sink in to the ground.
One great aspect of Swales is that you can use them to distribute water as well as fertilizer over large areas. I don't hear people talk about it as much in that way. Say you have animals in one part of your swale system and you need there fertilizer in another part, a swale at 1% grade will distribute it where you need it. even to areas where you can't graze your animals for fear they would destroy som of your precious plantings.
Good luck in your project! Whatever it is you choose to do.