Stashing bikes at south... How do you propose to get said bikes to where you can use them... Helicopter? Car won't do any good since the road is closed/washed out why you want the bikes to begin with... A blow up raft seems a better option for a large party. Always did want to try that option. Still would require a powered bike and rope to hide said raft up in the trees to snag on your way out and then float down the river. IE take bike, throw raft/pump on back, toodle up the road all the way to downy creek and stash it in a tree.
Backside of mixup melted out? Yea. Its southern/western exposure. Everything about 2 weeks behind. I wouldn't count on Kool-Aid lake being snow free though. High probability of it though.
The traverse is awesome. Best exit is going out via Garden Pass and Image lake. Adds another 2 days. You better tag Dome peak summit. Get that crevasse rescue training in.