Seriously consider an outfitter. Access in that area is difficult, land ownership can be tricky to figure out. You live a long ways away. You and he probably can't stay all season trying to get a ram. This is probably your cousin's one time shot at a good ram, or maybe any ram. Don't waste the tag.
I did a DIY, took 3 weeks off and got my ram the last day I had. I should note that from mid-April until the season opened just after Labor day, we scouted every weekend but 2, and I had Fridays off, so drove and glassed the area several extra days. Obviously the area was pretty local to me. The rams were elusive, and the big rams were nearly invisible.
If he has lots of time off maybe make a trip and scout around and learn the quality of sheep in the area so he knows what can be found. You need to learn about bighorns to be able to effectively hunt them. They are not quite like deer, elk, or pronghorn. Access and knowing about bighorns is where the guide can help your success.
Best of luck.
