Well squats is really a core-strength excercise. And, is a high-weight lift. At 15 years old; weighing 135 lbs... I was squating 305 lbs max 1 rep..working out 3 sets of 8 with 225 lbs; 3 days a week. That was for football (american)...and squats were a core-excercise like I said. A little weight probably won't help much...because you use your whole body pretty much when you squat; if you are doing it right. Be sure your feet are square with your shoulders; toes pointed forward; back straight; chin up. Then when you go down go until your thighs; knees; and butt are parallell. Any further can be murder on your knees. And don't just fall down go down slow; DONT STOP at the bottom; and come back up slow in one smooth motion. This is the proper squat. And I 'd say even the weakest person on the planet over the age of 13 should be able to squat at least 135 lbs if they know how to do it right.
If you want an excecise that would aim more directly at improving you on stilts..I'd guess Leg curls and leg press. See this pic for the press:
As you can see, his legs are kept more straight; like when bocking. When you squat..your legs will go outwardly in a way that is the opposite of how they will be in stilts, like this:
(that is a TON of weight, btw)
As you can see in the pics...in comparison..the first guy looks like he'd make a good bocker. Agile-"kangaroo" like muscles. You see, he has probably been doing leg presses, leg curls, and running a lot. Developing appendecular-strength. While the second guy, the squatter, has been powerlifting (squats, deadlifts, presses) developing CORE-body strength. It is apparent in the way their bodys are shaped. The second guy is built to be a perfect american football player. The first guy is your go-to bocker. So, thats why I advise looking at other excercises for strength then squats...
I'd very highly reccommend the leg press as it would work the muscles essential to Power-bocking. Like I said about squating, it is more of a core strength thing. These leg presses will make your vertical sky rocket; and high rep leg curls will increase your stride strength.
Have fun