Most importantly for these purposes, the range on the Model X is sufficient to drive from Palo Alto to Lake Tahoe (220 miles) or Yosemite (165 miles) without issue.
Towing a small pop-up camper? At highway speeds the whole trip?
Honestly I wouldn't be surprised if you ran out of juice before reaching Yosemite.
Grades and highway speeds have a huge impact on range IME. Not to mention an extra 500lbs in passengers, a couple hundred lbs in camping gear, and that's not even getting to the camper.
The type of miles you're driving definitely matters. A gas vehicle is most efficient around ~60mph. Maintaining maximal range in an electric vehicle is a bad bet if most of your driving is highway miles. At least if my Nissan Leaf experience is relevant.
Tahoe could be trouble with a camper in tow, but the distance to Yosemite is only 2/3rds of the published range for the Model X -- I'd be shocked if there wasn't sufficient range to get there. Curb weight for the X is ~5,400lbs, call it 5,500lbs with driver.. Adding 5 passengers averaging 100lbs (family of 6) and 200lbs of gear would only add ~13% to the vehicles weight which would only minimally impact range since drag is a much bigger determinant for highway trips.
I found a nifty little site that takes into account elevation / vehicle weight, etc. for the actual route. Looking at the Model S, base range on the road to Yosemite with normal driving is 240 miles. Adding 700lbs to the car results in a range of 210 miles. So a 40% increase in vehicle weight only corresponds to a 12.5% decrease in range. This can be partially mitigated by driving at a "3/10" instead of a "5/10" in terms of range-extending, which results in about 225 miles of range with the same weight.
https://www.fhwa.dot.gov/ohim/onh00/bar8.htm