I want to get better at skiing and I know leg strength is paramount. Are there specific leg exercises for skiing outside of standard stuff like squats?
My father was nearly an Olympic skier and this is wisdom I'm channeling:
Don't be so strong you aren't flexible. You want to have muscle endurance and flexibility over raw power. Flexibility also makes you stronger since you are more comfortable/strong in extended positions.
Core strength is more important than leg strength. Core strength gives you balance, but also makes your legs stronger. i.e. The more stable you are on your skis the easier it is for your legs to do the work. You want to be able to keep your center of gravity over your skis at all times.
a. Squats, lounges, etc. -> these are the standard leg exercises you'd find online and they will carry you until you are amazing. I'd also suggest leg raises that isolate your quads and groin exercises. The better you get, the more important having a strong groin is.
b. One legged squats. So without weights (or with them if you are really strong) practice squatting on one leg. These are pretty advanced and all I do to get "ready" for ski season nowadays since they work everything -- legs, core, and stability. The caveat here is that you want to avoid muscular imbalance and one legged stuff can do this pretty quickly if your aren't careful.
c. Every ab exercise and weighted ab exercise you can think of. Then do them twice. You want to be as strong as possible through your core, but -- again -- not to the point of being inflexible. Specifically you want lower ab and lower back exercises -- https://greatist.com/move/best-exercises-lower-abs
Good luck and have fun
If you are going to spend a day, or two. Just do it. However a week, or so need preparation.
Most people thinks about pure power, but that is not the case here. You need it, but not that much. More you need is stability. I can't recall where, but I've heard that bosu is not that good as all kinds of squats: Bulgarian, side leg, one leg (use TRX for support at start).
Endurance is also something that I'm usually suffering - wall-sit. Killer, for me.
Be sure to stay flex. As @Schlaefer wrote.
I can't see need for abs building, a specially if you are sitting at work. Most of that "best exercises lower abs" are building hip flexors. That is not always perfect. Usually I had problems with endurance, a specially quads. General core stability is always good idea, so I would include something like "rolling plank" from presented set.
The Concept 2 SKIERG:
Nordic skiing is an exhilarating and aerobically demanding sport, so it's no surprise that Nordic skiers are extremely fit athletes. The SkiErg makes this terrific aerobic exercise accessible to anyone. - Concept2
If your local gym doesn't have one, ask if they could put on a donation for all members to raise funds to purchase for the gym. Also, try this:
(1) Put on a pair of slippy fabric socks
(2) Get on a slippy wooden surface
(3) Slide horizontally left-to-right between two barriers
You could also jump between two raised platforms increasing the distance between them over a certain amount of reps. You might also consider limiting your oxygen intake with a mask while doing any one of these.