Hello, sorry for the delay. I did install my AC and enjoy it very much. I have not installed a brace yet. I had a local metal shop put a slight arch in two pieces of 7ft square tubing. Also had them fabricate brackets. I rebuilt my roof also incorporating some reinforcements for the ac. I'll post a few pics.
No way the old roof would have enjoyed supporting a ac. Plus it was leaking.
The support bars will be placed in approx location of the cross support wood.
Installed! At 72lbs. Took like an hour. Put it on roof opening. Install bottom plate and run 10awg to breaker.