@GrandRoyal - I think your overall approach is good. 2-3 leg blaster workouts per week, plus other stuff to maintain variety and keep your sanity. This is assuming you ski like me - not very often, but hard when you do. Also, I have no formal fitness training, so take my advice with that in mind...
FWIW, I am in similar shape now as I was last year. I didn't feel like I had problems with fitness on the slopes last year. I am a recreational skier. Last season trips: 2 trips of 3 days, 1 trip of 2 days, and 1 trip with 6 days (Deer Valley, PCMR, Whistler, and Breckenridge). I skied all days consecutively from 9ish to 4pm-ish. Time was spent roughly 50/50 on blues/blacks (plus some time on green traverses).
I have not done leg blasters before. I gave the workout a shot yesterday with 10 sets of the "minis" with 30 second rest between each. I found them to be quite difficult (I actually started with the 1 full set, but could barely get through it, so dropped to the minis for sets 2-10). I had to stop for a few seconds to take a break at 5 squat jumps before doing the next 5 to end each set. My legs are pretty sore today, but not too much worse than I feel after a good workout.
I typically workout 3-4 times per week doing Crossfit. I have been doing this the last 6 years.
I don't do leg presses. I don't have the equipment available, nor do I want to do them. I think you gain more by doing back squats, since you have to maintain balance and thus engage a lot of side groups you may not with a leg press. Of course, you need proper form to avoid injury and maximize gains. Leg presses are probably less likely to cause an injury when you are fatigued.
Anyway, I will try to work the blasters into my routine and see how it goes this season... The great thing about them is they require no equipment to do. Great for when I want to workout on travel, or I don't feel like driving to the gym.