Quick beta... we drove to within 300m of the parking lot with a great deal of effort and then then with a great deal more effort we turned the truck around with the help of a dozen people! There were 4 vehicles that attempted the drive up and all had some amount of difficulty. Recommend you just park on the plowed bit of road just off the Sea to Sky.
The conditions were amazing... fresh sugary snow on the ground with older snow barely clinging to the trees... only got bombed once thankfully. There is a solid track all the way to the lake but its on the summer route for now... later in the season there will be the slightly shorter winter route that passes between Lesser Garibaldi and Barrier Lakes.
Garibaldi Lake is still a couple months away from freezing over.
BC Peaks & Trails Hiking Group
Stay safe and have fun out there.