Hello Ruben and welcome back to the Disney Parks Moms Panel.
Several years ago I throughly enjoyed going on wonderful Horseback Trail Ride at the
Tri-Circle-D Ranch but I don't recall any other Guests walking alongside the riders; I'm presuming that was because the trail ride meanders in forested and wild grassy areas where walking on foot maybe a little tricky.
Before making your dear sons reservation for this outdoors experience I believe it might be a great idea to discuss your families particular needs by speaking with a Cast Member on the phone number contained within my previous link.
Have you perhaps considered taking one of the
Carriage Rides at Disney's Fort Wilderness Resort and Campground or at Disney's Port Orleans - Riverside Resort; these beautifully relaxing horse-drawn carriage rides are suitable for up to 4 adults
or 2 adults and up to 3 small children which of course means your lovely family can enjoy this experience all together.
If I can help sprinkle any extra pixie dust onto your upcoming visit to Walt Disney World Resort please pop back to ask me another question.
Have a great Disney day.
~ Jane