There may be sites or services that will give you a vacancy number.

I had allowed a contractor/handyman doing work on various properties I manage and own to live on site while he was doing the work in one of the apartments. 

My fiancée and I are looking to buy our first place maybe next year, I was hoping that I would be able to put 5 - 10% down and still get first time home buyer (cmhc site specifies primary residence, not investment properties).

Identify gaps in supply in that neighborhood and look at the property as a potential development site.

@Christopher BerggrenYou appear to be complicating  your analysis.  

I'm having trouble putting faith in a tech company to provide tech services that I can't even get setup.I give a lot of leeway to the program simply from the BP referral to the site... but has anybody used this yet?

If a rough estimate is all you need, I'd suggest doing a Google search as I'm sure there are plenty of sites that will give you such a number.

He just says he can hit those numbers if water/sewer and electric is on site.

You can find a ton through Meetup site or here on BP. 

So i spent at the site a lot of time.