Reader question: Taking a bike ride from Damnoen Saduak to Phuket

Finding a hotel or guest house in Thailand is no problem at all. If you take the route via the bay of Thailand (Surat Thani) there are hardly any sparsely populated areas and if you stay along the coast there are plenty of hotels and guest houses. However, if you opt for the route along the Andaman Sea (Ranong), I would still look for a few hotels in advance for some stretches and possibly book in advance with the option to cancel. This is usually possible until the day before with booking sites such as booking.com. Since most hotels and guesthouses have WiFi, you can see every day which hotels you can pick up and which you have to cancel. This way you are sure of a place to sleep and you can still pull flexibly. There are also plenty of hotels and guest houses on a large part of this route, but there are parts that are fairly sparsely populated and where you can find local guest houses but no hotels and guest houses for tourists. The local guesthouses are usually also adequately equipped but often difficult to find if you can't read Thai. I hope you have the necessary experience, because we are talking about a bike ride of about 800 km in a tropical climate.
Good luck

I happen to live along this route. Which route does the questioner want to use? Do they use the route via the Gulf of Thailand and then cross to the Andaman Sea once past Lang Suan? The route along the Gulf is already a designated cycling route from Hua Hin: the “scenic route”. Here there is no problem at all finding accommodation at any time. Many good resorts available, it is also a landscaped cycle route.
However, if they choose the shorter route from Chumphon, along the border with Myanmar, they would best follow the proposal and advice of David Mertens, described above. The route along Ranong may be shorter but much tougher as it is a very hilly course. The options for overnight accommodation along this route are further apart than along the coastal route.
Safe journey