Why are you concerned about his Sleep Apnea? I would think the bigger concern is his weight.
Are you planning a day hike, or overnight? If a day hike you can stay in motels that would help with acclimatization. For instance, Mammoth Mountain Lodge is ~ 9,000' elevation. Tioga Pass resort is higher (over 10K' I think).
If you are planning an overnight then the a battery/portable version should work provided you are not away from a re-charge for more than two days. Otherwise you might need an extra battery. The added cost may make a difference, but if you are coming from Florida (my guess), then maybe not so much relative to the overall cost. Also the portable version would/could be useful for other travel.
Does he suffer other conditions due to Sleep Apnea?
