The loop around down #5 Yellowhead instead of the #97 Hart highway isn't much farther and about the same time. I might have to take when I go north for hunting. Some guys prefer it.
I would think twice about using #99 from Cache Creek to Whistler. It's not an easy highway, you go right over the Coast mountains, but you do have a engine brake . I've seen a C-class motorhome with huge clouds of smoke billowing from it's front brakes after coming down on the Whistler side. I've heard of a few catching fire. Besides it's right through the fire area. The #1 Fraser Canyon is also scenic.