We are having difficulty sourcing sumacs (Rhus copallinum) larger than 6-7' locally, so we are considering digging some from an old field. We can find 8-10' plants in the ground fairly readily. Are there any special requirements for digging, balling, or transplanting them?
To ensure that your energies don't go to waste, chose the plants you want to dig up, dig a 1' trench around the base of the plant in a size you will be able to manage. Fill this trench with straw. Do this before the ground freezes. During this winter those sumacs will be putting out new roots into the rootball that they will take to the new location in the spring.
Early in the spring, after the ground has thawed, dig up your sumacs laying them on a tarp. You can drag the plants to their new location or even rent ball-dolleys (heavy duty dolley for transporting balled and burlapped trees and shrubs).
Fertilize with a slow-release organic fertilizer that includes mycorrhizae. This will help with the stress of transplanting. Make sure you water well and make sure there is really good drainage. Keep the root ball moist, not soggy until your sumacs become established. I'd build up a bed rather than transplant in ground level soil. This ensures good drainage. Make a trench all along the perimeter of the bed to carry away excess water.
Mulch carefully with 1" mulch, decomposed organic mulch. Too thick of mulch will tend to smother their shallow roots. If they were grown in clay soil and are being planted in sandy soils you will have to work at soaking the original root ball. A slow drip would make sure the water gets in the root ball and not be gobbled up by the porous sand.
Sumacs tend to have wide, fairly shallow, and coarse root systems, so the biggest concern will be keeping the root-ball in one piece. If you have a decent tree spade, it shouldn't be too bad, unless the soil is sandy. In clay, just be careful, and you'll be fine. If the soil is powdery and dry, wetting it can help, but only enough that it sticks; too much water, and soil will slough off the sides of your root ball.
Sumacs are hardy, and there shouldn't be any other transplanting concerns, if you get a good ball. The bigger, the better, of course, but tree spades are understandably limited. Water the trees very well after planting, especially in the fall, so they don't suffer winter burn/dieoff. Stop watering when the ground is likely to freeze.