Except for the shots of the snipe, why does it appear that you are looking down
from a great distance? Assuming you are shooting at 600mm it must be quite
a distance. I find that using a thick rubber exercise mat as long as your whole
body and laying down on it gets you down-to-earth without getting dirty. If acute
flexion of your neck is too uncomfortable, as it might be when prone on a mat
(and on your stomach) then a backpack stuffed under your upper body, from
arm-pit to arm-pit, it will take some strain off your neck. I much prefer to be
almost flat with my lens just inches from the sand, muck or grass for the most
interesting shots but that position cannot be maintained for very long. Taking
analgesics should not be a part of birding.