Flash input/help/advise

First off let me state that I am not a flash user, preferring to shoot with available light. Never have owned a flash but some how have dug out of the back of a closet a Wimberley F-1 telephoto flash bracket so at one time I must have been thinking about picking up a flash.
Fast forward to present day. I have found what I can best describe as a bird paradise. However, the majority of the subjects are sitting back in evergreens and in shaded areas. I will definitely need a flash but since it will be used only occasionally, I do not want to invest a pile of money into a system.
Camera is a 7D MKII and I'll be using my 100-400 IS II, sometimes with the 1.4x extender.
I know I'll have to pick up a Better Beamer extender and was thinking about a YongNuo 568 EX II and to keep it simple, a off camera cord like the Canon OC-E3. The flash will sit on the F-1.
Make sense or is there something else I should consider?
Thanks for any input/suggestions.
Ian (The flash dummy)

There are certainly a ton of options out there. I have a 568 EX II which works well. Instead of a cord I use YN-622C triggers, they've been flawless for me. There's a newer version of the trigger transmitter, the 622TX which gives you access to all menu functions without the need to go into the camera menu. What I have works and I don't mind using the in-camera menu to change flash settings so I'll stick with the 622C.

I live in a bird paradise. I guess I just can't imagine using a flash for birding. I run into similar situations as you describe here and just make changes in my camera to accommodate the particular scenario. That's what wildlife shooting is about. I very much prefer natural light in any given situation to artificial.

Looking at information on this flash extender device you referred to, I think the examples they show using the extender look, well, like a poorly lit flash shot.

I'm not really trying to talk you out of your idea.........but I suppose at the same time I am. If I run into a situation where the bird is in such a poorly lit area that it's just impossible to get the shot, then that's just the way it goes. But honestly, I don't get this very often given the capabilities of the newer cameras. Trying your idea won't cost too much money it seems, but I would suggest to you that what you spend is more time learning better techniques for shooting difficult light situations rather than attempting to use a flash. You'll get better, certainly more natural looking results.

Of course this is just my couple of cents worth, you need to do what you feel is right for you. Maybe some of the other birds guys will jump in here as well.

Just as an example, I caught this guy in a pretty dark area with a sunlight beam coming through the canopy, hitting the water and reflecting back up under the bird. One of the hardest things that I've run into when shooting birds, or, in fact, any wildlife, is waiting. Good luck to you.

Great shot. .... Just needed some fill-flash !

ETTL is nice to have but any flash will do because you just want to add a little light. You just need to get the exposure right manually if you don't have ETTL which is not hard.

Do not get a new 580II because you can a 600RT for almost the same cost. Look into a Yongnuo for an inexpensive flash with ETTL.

My recent on camera flash shots with a 7D2, 100-400 II, Canon 600 RT and better beamer.

In a dark jungle canopy.