My advice would be to take the antimalarials. Many people who are here longer than 6 months take them.
The risk is country-wide and higher during the rainy season - which you are arriving into. Yes, risks are probably higher in lake-side areas but it's really not worth taking a chance.
You can minimise your risk of getting bitten, but that will never rule it out entirely for a 6-month stay. DEET and nets are a good start, long sleeves, and trousers in the evening, getting your house sprayed and fans/aircon will help too.
You may want to bring your own mosquito net. Prices can get hiked up in the chain stores and at least you know you have one. We brought plenty of bug spray with us and haven't had to try to find any yet.
We also brought a year's supply of antimalarials for our entire family to do us through to our next visit home.
