I read your web page and the downloadable article. It's nice to see that my 'back of the envelope' number crunching mostly agreed with the numbers you presented therein.
I come from a background of measuring visual binary stars via video lucky imaging. Your multiple exposures to average out the seeing and using software to calculate centroids is virtually the same methodology. Where we differ and the source of my worry is that using the NP-101 at only 540 mm focal length will result in a rather large undersampling of the stellar images and reduced ability to calculate centroid positions to the accuracy you desire.
By the way, what software are you using for centroid calculation? I have used AstroimageJ with great success - it gives centroids to a rather optimistic 6 decimal places of a pixel!! Of course I only use three decimals for calculations (six decimal places of a 5 micron pixel is on the order of magnitude of larger organic molecules!) and report only 2 decimal places..
Of course, you are juggling the need for the widest field possible with the need for the greatest centroid calculation accuracy. Also, the shorter focal length allows you to get useful images of fainter stars.
When I measure binary stars, lately with 180mm and 200mm telescopes, I have routinely used focal lengths around f/30 or about 3000mm. At this focal length and with this aperture separations to 0.01" accuracy can be measured and published. My colleagues and fellow amateur binary star enthusiasts (see http://jdso.org) also use such long focal lengths and 0.01" reporting accuracy is just about the norm. Very few, if any, of the amateurs submitting measures resulting from video lucky imaging to the JDSO use telescopes smaller than 200mm and focal lengths less than f/15.
I recognize that if you were to use f/15 or more with the NP-101 you wouldn't even get the entire eclipsed sun in the field of view........
You are hoping for similar accuracy with a telescope with half the aperture and a very short focal length. For field of view reasons you really have no choice in this - I understand fully. I very much hope that you do achieve this success (and prove me wrong! ) and I look forward to seeing your results.