Not so easy if you're registering your own company. 2 MTHB paid up capital, Register VAT, pay minimum wage (full time employment, part time doesn't count), pay personal income tax, have rental agreement for business premises. They come and audit your company. Just to name a few of the requirements. (Experience gathered in Chonburi/Rayong).
not sure about Cambodia. I've taken the car to Malaysia a few times but even there it's only the third party insurance they offer. Traveling by land is different in ASEAN. Too much procedures and restrictions.
don't drive there. Last time I heard it's not legal to drive a Thailand registered car in Cambodia, no insurance also. It's different from going to Lao PDR or Malaysia.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.