Go straight to immigration tomorrow morning and get an extension. You'll have to pay the usual 1.9k baht plus 500 baht fine for a day overstay which is absolutely fine since it's under 90 days IF you "surrender" to the authorities. If by any sort of silly chance, you get stopped and your visa checked, you're fucked, in the fashion Robert said above.
So as soon as the sun goes out, ride to immigration with your passport and queue. You'll be good by lunch.