ditch the side by side and hit the miles and miles of awesome single track in the area
What TRD270 said. You could do most of the loop for Devils Race Track. There is one section that climbs up in the sandstone that you may need help with but its fun. You could also do the Blue and Green Trails. I just dont know your ability.
If you have ridden over Willard Peak to Mantua then you could even ride 5 Miles Of Hell. I would suggest you add the Orange Trail to that list. How well does your father ride