Review the attached link. The BEST soil recipes you can use are addressed in this first post. The 1-1-1 formulation (aka "gritty mix") is the one I'd prefer for woody plants but either will work fine.

Here is a link that might be useful: container soils

Hi Rhizome, here's my advice:
GET THEE TO A TRADE SHOW, as soon as possible. Perhaps you were able to attend the PANTs show last week in Phily. At these shows you will meet suppliers and compare prices and get the best deal. Also become active in your state's Nursery Association, meet other container growers, make alot of visits and ask alot of questions.
In my area we use pine bark amended with slow release to include trace elements. Ground limestone also depending on what species. In Spring we also include top dressing of slow release plus fertigation.
I do not regard the link for container soils as appropriate for you, that looks more like a gardening mix. In my area no commercial grower has used perlite for his tree soil mix in 30 years. Our local supplier sells 4CuFt perlite/$11.34 maybe thats why. Its gonna be amazing how quickly those 15 gal cans swallow up the soil. I highly recommend that you set the plants down so they don't have to be moved again until shipment.
I'm curious, sounds like you won the bid for a large contract right? Do you have the manpower and equipment to mix this volume of soil? Are you going to use trickle? How are you going to overwinter?

Bark, sand, slow release fertilizer.

Thinking out loud, if you left out amendments could bark along be used in the propagation bench? Posting from Maryland. Any other growers from Eastern US here? What do you use?