... Chris and I were aided somewhat by the fact that I had been pretty far up Skyline Ridge before, and with the addition of a GPX track could essentially sight to the pass we needed to hit, and this was pretty apparent even without daylight (though it wasn't full moon, it also wasn't new moon, so there wasn't zero light by any means.
Also, in many ways, the scree field was the perfect thing to have to cross at night, because there was zero route-finding necessary, just point and schlep, and try to keep elevation (the consistency of the scree made this surprisingly difficult).
The route we took didn't go up and over the Sky-Pilot - Co-Pilot Ridge per-se, we skirted the south sides of both. Going up and over was a possibility, and I know people have done so, but we didn't even want to consider even minor glacier travel at the end of a long day, nor carry any additional gear to do so with confidence.
We(I) did pull out the gps quite often at points just to confirm that we were on the right bearing ... we always were which is testament to the obvious route usually being the best one / the one that others would have gone also, so the GPS was a nice verification device, but most of the navigation itself was done with common sense as the driver.
There was one place right after Mountain Lake Hut that we tried to take a shortcut, and got cliffed out several times, and if we had been a bit more patient and followed a track I had saved, we could have avoided an hour of putzing about.
Given that in general, the alpine trail is a common sense one, it wouldn't require that much by way of flagging / cairning to make the trip much faster and simpler ... Those little pauses to verify GPS certainly add up significantly ... undoubtedly several hours worth over the day.
I think if the considered HSCT-North were to happen, some kind of linking trail is quite necessary, not only because the drop to Porteau Cove isn't really that fun, and the run along the road is kinda dangerous, but also because eliminating that extra distance would certainly be somewhat necessary for most to get to Mountain Lake Hut in a day, whether by the valley like we did, or via Capilano and HSCT-North.
Projecting further, the connection all the way to Whistler basically already exists, it just needs to be stitched together, and once done, it will make quite an awesome trip to do ... but also be quite accessible and safe since despite being in pretty wooly terrain, one also is never that far from civilization should something happen.