First of all, I assume that you are wise and you are going with a group. I have soloed it once in May, in a day, and it kicked my butt severely. Sleeping overnight at Lake Helen is the way to go. I also assume that you know what you are doing with avalanche safety. That route is called Avalanche Gulch, and it is for good reason. We were standing there in camp at Lake Helen in the late afternoon, and the guys from the Mountaineers had just pulled in and set up. Right then, right before sunset, an avalanche started from Red Banks heading down, and it just kept going and going. Everybody stood there in amazement as it swept down. However, if you study the curve of Avalanche Gulch, and if you saw the intensity of the slide, you would know that it was going to turn away from camp, which it did. However, in the interim seconds, the Mountaineers were petrified, and they didn't know which way to run. Finally, the slide stopped to the right of Lake Helen. The Mountaineers immediately announced that they were not going to the summit in the morning, so they broke out a bottle and then bailed the next day.
If you head out of camp at 5 a.m. going for the summit, it tends to be pretty cold. However, if it is not too windy, you might be tempted to leave behind some layers since you will be hiking upward and generating a lot of heat. That's probably not wise. You might need it later.
One year I got up to Red Banks with normal warmth in my down parka. But then the wind was blowing awfully hard, and it sounded like a freight train. Above the top of Red Banks and heading up Misery Hill, the wind forced me to a crawl. When I got halfway up Misery Hill, it was too much, so I rested flat on my back (huge down parka on), and that was the only thing that kept me alive for the next 90 minutes. I could have bailed, but I would have been pretty cold going down. After the 90 minutes and the wind had not broken, I managed to get back up and crawl up the rest of the way up Misery Hill. Once above it, I could stagger over to the summit pinnacle, and then I made it up. A few hours later, I made it back to camp safely, and I think I was only one of maybe 2 or 3 people who summited that day. My point is that if I hadn't had that huge down parka (a so-called 7000 meter parka), either I would have had to turn around, or else I would have frozen my butt right then and there. Personally, it is extremely difficult for me to bail on a mountain when I have already climbed nearly all of it.
I don't know you or how warm you stay. I don't know all of your clothing items. So, I can't say for sure. That weather was the worst that I had ever seen near the summit in 22 summits (May only). Do you think you are lucky?
The glissade pants are interesting. If the snow is soft, then anything will work, and probably work good. If the snow is more ice, then it will carve up good pants. If the snow has a good scatter of volcanic sand and bits, then it will slice up the good pants even worse. I've seen people wearing just about everything up there (even cotton jeans!). If you are not good at glissading, then there is a safety issue from excess speed, so it wouldn't hurt to have an expendable "seat" over the outside of your good pants for slight friction. Old blue jean shorts, maybe? One guy made a "girdle" out of some old truck inner tube rubber.
I saw a terrible accident one time, just below Red Banks as I was descending. A fool was wearing crampons and attempted to glissade down. He caught a point, which flipped him, and then he was sliding out of control. After he had good falling speed going, he collided with two bystanders. The man was knocked sailing downward for a way, and his lady was knocked even worse. She sailed downward for well over 1000 vertical feet, maybe 1200 or so. She came to a rest, and a Forest Service ranger appeared out of nowhere to do first aid. She survived.
I wish you luck. Pay very close attention to the weather forecasts. Write me into your will.