George Sheehan (you may be too young to remember him but he made a pile of money writing running books in the 70s and 80s) once said, "Life is a conspiracy to keep you from getting your training in."
If you're going to keep on with the sport and really get to whatever your full potential is you're going to have to learn to deal with that conspiracy and make adjustments during times when your routine is disrupted. When that sort of thing happens you go into "maintainence mode," i.e., you focus on doing what you can and minimizing damages.
There are 24 hours in a day so if you ride in a car for 14 and sleep for 10 you've got two hours left for running. Even if you only use 30 or 45 minutes of those two hours to run you'll at least be maintaining your level of fitness and most likely improving it slightly. Lydiard always said that even a 15 minute run brings benefits. Don't ever fall into this all or nothing mentality that says if I can't do all of the running I want to I won't do any of it.
Ski resorts have roads. They are very good about clearing those roads of snow and ice. They have to or they'd have no customers. You can run on those roads. There may be snowmobile trails and those are quite good for running. No, it won't be as pleasant as being on some pristine trail and it may be at an earlier or later time of day than you like. But you can do it. Some resorts also have fitness rooms. Fitness rooms often have treadmills. You may not get in that full 120 miles you mention but you can get in a reasonable chunk of it.
The mature thing to do here is to go pleasantly on the trip explaining to your folks that you'll be spending some time running while they're skiing, socialing, eating, etc.. Your parents deserve to have a holiday doing something they enjoy and lots of us would be hesitant to leave our high school aged kids alone at home for days on end. And for what it's worth to you, Shorter used to go on skiing holidays.