Can I cross at Mae Sai for a 30-day visa exemption if my Ed Visa expires on May 30, 2019?

I need verification of my plan/ understanding, please. I have an Ed Visa from June 2018. Its last day of validity/ the last extension from it expires on May 30, 2019. I am planning to do a Mae Sai land crossing on May 30th and getting a 30-day visa exempt stamp. I anticipate they might want to hassle me about not really being a tourist, but 1) I haven't done a Mae Sai or land crossing into Thailand in about 1.5 years, and 2) I will have a ticket showing that I'm traveling to the US in July/ within the 30-day visa-exempt stamp's time limit. I can do this, and don't have to cancel my visa at an Immigration office, right? Simply crossing on that last day (the 30th, or even on the 29th for that matter) would do it, yeah? They will likely grant me the 30-day stamp since I haven't abused the system, yeah?