Tourist Visa (Multiple Entry)

Hello Group. I am applying for a multiple entry tourist visa that is valid for 6 months, multiple entries, 60 days for each entry. My question is, how long to need to show documentation for hotels booked? I plan to arrive and spend about 5 days in Chaing Mai, but beyond that it is difficult to determine my exact schedule and I hesitate to make any more confirmed hotel reservations. After 2 or 3 weeks in Thailand I plan to Visit Vietnam and Philippines for a couple weeks, then return to Thailand for another 5 weeks in Thailand. No plans are concrete after I arrive and spend 5 days in Chiang Mai. All other documentation is simple - Flight tickets, Bank statement, Photo, Passport are simple, but it's the accommodation I am struggling with. Thank you.

Hi all I am a teacher in Thailand and I need to return my work permit ASAP to my school. My visa expires on the 22nd Jan so I’m unsure what the best option would be? I am in Chaing Mai for NYE so could possibly do a run in Laos. Please msg me if you have any advice, thanks!