Seems you can't add waypoints (in RWGPS) unless you have a subscription.
List of potential stops along the route
37km Neufchatel-en-Bray - second breakfast - Coffee and Bakery stop (our ferry group stopped here at Nemrod bar in 2015)
94km Etrepagny - Lunch - Various pizza places, bakeries, restaurants, bars
121km Gasny - Supermarket and bakery
131km Bonnieres-sur-Seine - Various places including pizza, bars, cafes etc.
144km - Breval - Our ferry group stopped here in 2015 at the kebab / burger / takeaway / cafe.
I have changed the route to leave the Avenue Verte after the first stop and bypass Forges-Les-Eaux as it gives simpler navigation (with no change in overall distance) along the D1 for the next 30km.