describes my experience at a Thai university for a few years when I first arrived in the late late late 90's
15 hrs a week of class time, plus the summer off with pay all for 35k per month all in. I doubled that or more with another 3-5 hours of public lessons each week in the evenings
I arranged my classes so I worked three days per week and between us, the foreign teachers signed each other in on days we were off-site.
During the summer the lower-level Thai teachers would sign the foreign and senior teachers in so we could travel. Sadly that became problematic in my final year before I joined the corporate world. At the ripe age of 25, it was a brilliant gig while it lasted.
As I understand it, English teachers don't get paid all that much more now.