Hello Bob
Looks like a you need a "Professional Arborist" to do the work correctly and with some level of confidence on the durability of the project (to much potential liablity for someone that is not insured to take.)
Look for the local arborists to see if you find one interested in Amateur Radio Operations and he or she would be able to help you get this Antenna Installation project completed safely.
No many Recreational Tree Climbers are willing to take the risk on something like this.
my 2 cents.
Here is a _link_ I found in Google.
http://www.illinoisarborist.org/CertifiedArboristsNew.htm