swiss topos are online – http://map.geo.admin.ch/
There’s about 4 or 5 routes that I know of to get down to the Rhone valley – get to Monthey and then you can get the train back to Champery and you’re back in the PdS lift pass area.
Also managed to ride to Lac Leman last summer: Morzine > Chatel > Morclan > Lac d’Arvouin > Col de Verne > Lac de Tanay > Le Bouveret.
And a very good overnighter can be had if you ride down to Monthey, across the valley to Bex, then get the train up to Gryon – ride up about 600m to refuge Giocomini
Next day you get a top drawer descent back to Monthey -> train to Champery -> home by Lunch time.