Hi, I just did the border bounce at dannok (sadao) with a multiple entry tourist visa. It is a 1 hour drive from hat yai. I had 20.000 , flight ticket and booking of accomodation on me but they did not ask for it. It is 150 bath for the motorbike driver to drive you in and out of Malaysia and back to Thailand. Very nice immigration staff. It took me 20 minutes only. Good luck !