Direct W/L comparisons without many shared opponents is very dangerous. You need to start examining the records of the opponents as well as examining SOS to help build a better picture of the road each team walked.
For example, Dinwiddie's opponents were 61-39, Cal Preps gives Dinwiddie the #2 SOS in all of C4 out of 51 teams while Kettle Run's opponents were 45-55, Cal Preps gives Kettle Run the #34 SOS in all of C3 out of 55 teams.
Total W/L record per opponent and sorted by SOS (in their respective class) for GW:
C2 Martinsville 48-51, tied for #16 SOS out of 49 teams
C3 Staunton River 56-44, #11 SOS out of 55 teams
C3 Tunstall 52-47, #32 SOS out of 55 teams
C3 Bassett 46-54, #35 SOS out of 55 teams
C3 Magna Vista 43-57, #37 SOS out of 55 teams
C4 Dinwiddie 61-39, #2 SOS out of 51 teams
C4 EC Glass 63-36, #3 SOS out of 51 teams
C4 Amherst 55-44, #8 SOS out of 51 teams
C4 Halifax 56-44, #26 SOS out of 51 teams
C4 Mecklenburg 50-48, #44 SOS out of 51 teams
Total W/L: 530-464
Total W/L record per opponent and sorted by SOS (in their respective class) for Sherando:
C3 Warren 63-37, #20 SOS out of 55 teams
C3 Fauquier 53-47, #29 SOS out of 55 teams
C3 Brentsville 51-49, #30 SOS out of 55 teams
C3 Kettle Run 45-55, #34 SOS out of 55 teams
C4 Liberty 61-39, #27 out of 51 teams
C4 Millbrook 54-46, #41 SOS out of 51 teams
C4 James Wood 48-52, #43 SOS out of 51 teams
C4 Handley 38-62, #48 SOS out of 51 teams
C5 Lightridge 60-40, #12 SOS out of 48 teams
C4 (WV) Jefferson 52-48, #9 SOS out of 21 teams
Total W/L: 525-475
So on the surface even the opponent W/L is evenly matched but when you take a look at SOS it becomes pretty clear that GW's opponents by and large played more difficult, successful opponents.