Sigh....I REALLY dont want to come off as a smart ass....
Your original post asked for an IPM program that only included injections and only 1x per year.....that is not an IPM program.
This is what I tell my potential client, weather it is 10 trees or 1000 trees.
My IPM program consists of X site visits throughout the year based on GDD and the plant material that is onsite. These site visits include diagnosis and treatment as needed. Your price is X per visit and Y for the year.
We estimate all the time during the winter because I can identify what type of plant material is on site and the potential problems based on my experience and knowledge of MY area.
Just because this site is large does not mean it is different than a bunch of average residential houses.
You have yet to answer a single one of my questions except to tell me that 600 ft of hose wont reach the area of service.
You have mentioned River Birch, Maple and Crab apple so far, what are your potential problems with each of those trees? That would be a good starting point in putting together a program.
But since you seem to think we are just giving you a hard time and not answering your questions and you have all the experience you need to do an IPM program except how to ID, diagnose, treat or price....
Here is my answer: imidicloprid Mauget caps and charge $2 per tree, you should be good....or get a spray rig that will get to your service area and continue with your pseudo IPM spray program.