My friend top tenned at the OD 100 on a walker so is giving me hope for the breed, just maybe Bo isnt up for it.
And from what I heard, Broxton was a hellacious ride metabolically even for a lot of seasoned endurance horses due to the weather. So perhaps trying the same idea of riding slowly with your gf's tb at a ride that isn't 110 would be what Bo needs.
There is a woman (Mary Coleman) who has thousands of miles on exclusively Morgans who talks all the time about 'morgan weather.' If it's not morgan weather, she doesn't ride because she knows her heavier horse will not be able to pulse down. No way in hell was Broxton morgan weather!!