Alexander - where are you located inside Thailand.. You just need to do a 'border bounce' as you said - exit Thailand - get stamped out - then reenter within minutes. Where you are can of course have a bearing on the easiest most convenient border crossing to use.. Also the Non Immigrant multi-entry visas like you have usually get an easier time of it versus tourist visas and Exempt entries but you could still be ask to show cash as has been suggested