One of the greatest gadgets I have for riding is a portable Garmin GPS. It calculates your distance and speeds not to mention rest stops, routes, etc.
Anyone doing trail riding should consider checking it out. It is simply a great tool.
I down load my trip information onto my pc for my conditioning schedule.
I would love to help but it really depends on the horse. My horse Dobe walks so fast that other horses have to jog to keep up. But, my dad's horse Pokey walks so slow, he can't keep up with anyone. I walk faster than he does. LOL.