The route is shoulder on hwy 99 almost the entire way. Be careful with the u turn on Callaghan, and again coming down Callaghan and making the left onto 99. Then again be careful with the u turn riding toward Pemberton. Other than that, and the traffic in and out of the village, it's just shoulder riding on 99.

Edit: recon ride isn't even necessary. The bike route is dead simple, as is the run on the paved trails along green lake. Road undulates the entire way, save for two or three steep descents toward Pemberton, and then same climbing back out of Pemberton toward Whistler. But take any excuse to visit Whistler. :) It is nice.