Thanks for the answer. To close the loop on if wider is at all better on decent roads. It would be really interesting to see the optimal setup for the same model of 25/28/30mm tires on the same wheel compared (combination of rr and aero) on decent road surfaces with pictures of the road surface. I’m very skeptical that 28mm is going to be faster than 25mm, and I assume 30mm will be the slowest.
Then add an accelerometer glued to the seat post also, and we can get data on comfort and hysteresis loss in the rider to some extent. If you need help analyzing the vibration data, I can help as I do some of that at work.
I am going to try and make this happen. I have a trip scheduled and I can easily get 3 identical sets of wheels setup with 25, 28 and 30.
The riders have blacklisted me since i made them do 3 days of 100km/day of CRR testing at pretty hefty pace on crappy roads. I may have to do the tests myself 
If I can make it work out, we can align on how to collect the accelerometer data.