Where you're located you have about 10 weeks before the first frost, correct? Is that time enough to harden off? I'd think so.
I guess what it gets down to is, do you really have to?
Are you going to be showing it or anything?
How healthy/vigorous is the tree?
Bottom line I wouldn't unless I had to this late in the year.
You'll be robbing the tree of energy it could put back into the roots for the spring.
Are you really at the point where this is the type of ramification is necessary?
Couldn't you get the desired results by spring pruning.
Food for thought