If that was the biggest limb I was cutting would be tempted to leave the chainsaw in the truck... (Silky Sugoi...I have a Samarui too, it is nice, but not for making money...good for recreational climbing)
Do upgrade those to auto-locking carabiners, not screw locks.
Yes...back up throw bag (and second line) is a life saver at the right time. (I might have heard of a "friend" who actually had to go to 3rd string 
I have a foot ascender, and have used it only used it a couple of times. A micro pulley is a huge plus, I'd recommend that way ahead of a foot ascender.
That proper saddle will help. No doubt, it is hard work, but it is amazing how a little comfort cuts down on the amount of energy you burn.
Don't hesitate to have your helper put down the camera and send up a bottle of water.
Finally, do NOT prune red oak during the growing season (Oak wilt). Hold off on those until September/October.
Enjoy and be safe!!!
