Some other cheap ideas to make tenants happy: add some outdoor furniture so tenants can enjoy the nice weather and socialize with one another. 

Sunshine, access to the outdoors, great food and drink scene.

@Michael Baum, the bar/food area seats 25 legally inside and then has outdoor space as well.

Now having said that if you put cameras anywhere other than covering outdoor space such as entrances then you are not going to have many guests.  

Lovely setting and outdoor space.  

In the amenities list you can still mark the yard as shared, or patio, or anything other outdoor space that may apply to.You could also consider creating 3 separate listings - one for each smaller unit, and one for the combination of the two units for larger groups.

The property sat on 11.5 acres, 5-1/2 or so that were wetlands and unusable. 3 buildings totaling 10,000 square feet; 74 outdoor parking spots.

Break ins are more common in the off season because of accessibility, and you'd have to worry more about outdoor furniture being stolen.

  $300 for electrical to garage and outdoor spigot is very cheap and as you said, no way that an electrician. 

You can always make the justification that if your property is really nicely appointed (nice kitchen, nice furniture, fresh paint, great interior decor), sleeps a bunch of people, has fun amenities (hot tub, swimming pool, pool table, outdoor kitchen area, manicured firepit) and things for people to do: they will book it out regardless of where it's at.