"The R5 with the 200-800 is a little faster than the R7, but then I still lose magnification." - the magnification of the lens should be the same, no? With R7 you just have the detail spread on more pixels and you can crop more. I have no idea where you are taking these photos but if it's your backyard (I think you have a feeder there?) I would sacrifice my old tent to make a hide at closer distance (I mean I would cut a window on the site looking at the birds, the entrance should be on the opposite site). Let it stay until the birds get familiar with it's presence and enjoy?! Of course instead of tent you may use other means but you got the idea.
For luxury you may add there a chair and even a small table for the coffee and snack...
Well, here I got over the top

ROFLMAO

but to dream is not a sin

!