Climb up the Rainbow Lake Trail from Rainbow Falls Trailhead, climb up that annoying baby headwall to gain the valley, climb up towards the summit of Sproatt (either climbing up the forest or meandering up the valley to the col depending on avi obvs), but then ideally ski down one of the NNW facing gullies. Check out the topo on the Avalanche Canada website and the pages in Baldwin's Exploring the Coast Mountians on Skis for more info, or message me. 

Expect something like 14km and 1200m vert. 

Logistics: meet at St Davids at 6:00AM - we'll decide carpools there. (Unless you're coming from Whistler/Squamish obviously).