Today I crossed into Malaysia at the Wang Prachan border near Satun. I was told at the border that I just have to stay overnight in Malaysia and then I can re enter Thailand with a 30 day visa exemption tomorrow. Very easy and fast through immigration on both sides. (my 60 day tourist visa, already extended, expires today - Australian passport)
Nice motorbike ride from Ao Nang too and a beautiful national park on both sides of the border here.
TLDR : Answer Summary
The user reports a smooth experience crossing from Thailand to Malaysia at the Wang Prachan border, indicating that staying overnight in Malaysia allows for re-entry into Thailand with a 30-day visa exemption the next day. Comments from other users suggest this may be a common practice at various borders.