Hi Brian,
I think you're right to be concerned about the competition and I agree with the advice given by George and Bryant. Though pawpaws are fine in part shade (young plants even need protection from too much sun) and sour cherry is shade-tolerant, the other varieties you want to grow need sun to thrive, avoid disease and ripen their fruits well. The amount of sun they receive will influence the sweetness of the fruit: while you can grow cooking pears in part shade, dessert pears need lots of sun to bear delicious fruits.
That being said, the size of fruit trees is mostly determined by the rootstock and if you want to grow a large variety of fruits and avoid too much competition, you might opt for dwarfing rootstocks for some of your trees.
Also please consider this: when you want to grow a varied herb layer, there has to be enough light under the trees as well. For this reason, wider spacing of trees is often recommended for forest gardens.
If you're interested, here's the design of our forest garden :
There are also several videos about how we design the herb layer on our YouTube channel.
I hope that helps!
Greetings from the Netherlands!
Vera