Nice report. Good to see average mph as it is as useful as average mpg when trying to make comparisons across vehicle spec, climate, terrain and leaving some fudge factors for driver skill or emphasis during use. Highs or lows don't really mean much, it is averages that count!
51-mph also correlates with sensible daily travel times (rest breaks, fuel + food, stops, etc), so as an overall judge of the way the driver is using his time it also says quite a bit about whatever else he reports. Context.
A nice rig (for those who haven't taken the time to read all the OP's posts: recommended).
1990 35' Silver Streak Sterling
; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 10-cpm solo, 18-cpm towing
Sold: Silver Streak Model 3411