First thing is.. Your current work permit is very specific to what you are doing now..
Doesn't count under a new business.. You would need a new work permit...there is nothing in terms of law stopping you per se except driving a commerical vehicle
Foreigners can technically own land under Article 96 of the Land Code which allows foreigners to purchase 1 rai of land for building a house if they invest THB 40 million in BOI approved investments in Thailand
However In practice not aware of anyone who has actually done this..😁
You need a work permit and must bring your personal effects into Thailand within 6 months of arriving.. Only other route is returning Thai national who has been out of the country at least 12 months 👍