I read a story a year or so ago about a small 9 meter sailboat stopping in Vietnam. Sailed by a Viet war vet, he wanted to come back. When he "checked in" with the port, customs, and immigration, they had no idea what to do with him. There were no regs on 9 meter sailboats. The charged him as the smallest vessel (100 meters) that they have ever cleared. It cost him thousands. He left soon after.
Because there is no GA, there are no GA rules. Or customs or immigration for GA crews.
Not a good idea. Sorry. Thailand is much more welcoming, in hundreds of ways, including GA.