Based on the new proposed (easier) route, here is an overview of the first part from Lyon to the restaurant Les Cèdres that Papi liked so much, which could provide a good place to stay if we decide to split the journey in two legs.

This route is pretty much flat going down the Rhone valley in mostly industrial areas… There’s only one short climb between Tain-l’Hermitage and Granges-les-Beaumont pictured below.