New Member & Request for Advice/Info Re: Thailand

[Fibonacci]

I will be leaving from Cambodia, I just don't know the best way to get to Thailand... if I am in the Southern Cambodian Islands (Koh Rong Sanloem), do you know if I can easily make it to Koh Chang or Koh Kood? When I say easy.... I mean in a day or less! Ha! I assume I would go back to mainland Cambodia then go to the nearest border crossing. I was hoping to avoid Bangkok unless I really need to transit through there.

You will need to get from Koh Rong Sanloem to Sihanoukville then 'theoretically' (lol) you should be able to take an intercity bus to BKK via the coastal route (Krong Kaoh Kong-Chanthaburi-Klaeng-Chon Buri-Bangkok) and hop off at Trat in Thailand.
Sihanoukville to Bangkok - 5 ways to travel via plane, bus, minivan, and car

All ferries to Koh Chang leave from the main terminal at Trat.
Koh Chang Ferry passenger information and timetables for November 29, 2019

Ferries to Koh Kood leave from Laem Sok, near Trat.
Koh Kood Ferry & Speedboat Timetables - Updated November 2019
Getting to the Laem Sok pier near Trat in Thailand from where this boat to Koh Kood departs.
Hope this helps... Good Luck