As a five year old my mare was very wide backed and mutton withered, so I purchased the Bob Marshall Sports Saddle and have been very satisfied with it. You did not metion the age of the gelding, but you can expect his back to change with age and conditioning. Because the sports saddle is *treeless* it easily accomodates these changes without fooling with gullet & panels. The saddle is lightweight and relatively inexpensive. Of course there is not one saddle that is guaranteed to fit every horse but there are a lot of different shaped horses in endurance using this saddle. Also there is a good market for the sports saddle so if it doesn't work you should be able to sell it easily and recover most of your investment.