Single entry visa vs multiple entry visa

I am a U.S. citizen and am wandering if it is possible to apply for a multiple entry visa. I am working for a non profit based in.the US, but will be traveling a lot in the region for 10 months and we are hopin that I could make Malaysia my base. I won't be working in Malaysia,  I'm concerned about entering up to 8-9 times each time single entry.

How many days are you expected to stay in Malaysia after each entry?

Typically between 2- 5 weeks.