Maybe it's because Foreigners are not allowed to participate in photography,
If a freelancer needs to be physically present in Thailand to carry out their work, it can be seen as a job that could potentially be held by a Thai resident, leading to disqualification. Just a thought.
At Ranong, you need to go to the Thai immigration office and they will inspect your documents. Once they agree you are fine to be let back in you agree the return fee with the boat guys 200 baht each way is fine - Myanmar is visa free for 14 days but travel is restricted once there. Once you get to Myanmar get off the boat and someone will take you to the immigration which is a few minutes walk away where you will need to pay 500 baht. Go back to the boat, wait for it fill and go back to Thailand.