I am not able to see the plan you have uploaded.
Anyway, here is my suggestion I think you can skip the kokan part between Mumbai and Dapoli. Experts can add their thoughts.
Day1 - Reach Dapoli - a day is sufficient for staying here. Maybe Karde/Murud beach
Day2 - Start from Dapoli and take the Maharashtra coastal highway no 4 till GanpatiPule.
You need to use ferry at 2 locations Dabhol-Dhopwe and Tawsal-Jaigad.
Refer Homepage - Suvarnadurga Shipping & Marine Services
. The road is very scenic along the coast.
Near Ganpatipule, you could stay at Malgund, GanpatiPule , Bhandarpule.
I stayed at Bhandarpule. Its about 4-5 Kms ahead of Ganpati Pule. You should take the Arey-Warey road from Ganpati Pule. This road is simply superb!! My limited vocabulary will not do justice to the beauty of this road.
Visit temple and Ganpatipule beach.
Day3 - Spend time on any of the beaches Bhandarpule/Arey/Warey. The current is strong and the beaches are isolated. So do take precaution if venturing deep.
Day4 - Proceed towards Malvan/Tarkarli via Ratnagiri using the Arey Warey road till Ratnagiri. I have not done Ratnagiri-Malwan section on the state highway 4, so not sure which road to take between this - either the national highway to Goa or the State highway 4
Day5 - Snorkelling/scuba in the morning and Water sports in the evening. Devbagh near Tarkarli is very good for water sports.
Day6 - Start return journey