The author of the comment is 100% right. If you tell immigration officer that you will work on tourist visa (non DTV) you go home immidiately. Anyone who was doing visa run on tourist visa will tell you this. Never admit you work.
You cannot use cheap travel insurance as it requires home country insurance. They just pay you flight ticket home in worst case. Be sure to read T&C. You need something better.
Malaysians do not need visa as a tourist (visa exempt entry). Any kind of visa (do not confuse it with visa exempt which means you get no visa when you enter) you will have to apply online instead of going in in-person
60+60+45 = 165 is still under 180. But you close to this thershold. I recommend getting extension instead of risking. If you have a course -> get proper visa.