Keep property as duplex or change layout to a three unit?

[Lester Schmitt]

I purchased a 2 unit building in upstate NY in a small village where the Hospital is the major employer. My target tenants are traveling nurses and doctors who the hospital employs for 3-12 months periods of time. I have finished and rented one unit for $1500 per month, which covers my expenses. The finished unit is a two bedroom 1 and 1/2 bath two story unit.
The side I am getting ready to renovate could be easily split into a one bedroom apartment upstairs and a one bedroom apartment downstairs. These would rent for $1000 apiece. Utilities for all apartments would be separate.
I asked the local codes enforcement what would change if I did make this into a three unit and he warned me that I would be required to have a sprinkler system in all units and an alarm system.
I could incorprate these changes into the side to be renovated, but retrofitting them into the already completed side would be more difficult.

I am looking to hear anyone's experience as to what the cost of a sprinkler sytem/ alarm system might be and if there are other incremental costs or regulations that should be anticipated that I haven't thought of.

For the extra $500 per month income and some decrease in insurance costs, I am motivated to do this, but the regulatory hassels are less as a two unit.

What do you think?