I own a 1/4acre chunk of suburbia and I've been thinking about an invisible fence (a family member got a deal on a gas-powered super-edger on CL for cheap, vs back-breaking post hole digging) for my 1yo lab mix.  Given the size of the property, there's only a few feet on each side of the house to the line so I'm looking at just putting the fence around the back half of the property, or about 75x35'.

I'm just looking to let her outside to do her business on her own, so I do not have to parade her all over the property until she finds the perfect spot, she'll be inside whenever I'm not home.

One thing I cannot find in the online literature for the various fences is how close the dog can get before the beeping/shock starts or how small of an area is the minimum, is this too small of an area to consider?  

Kharn

The size of the field is adjustable.  Anywhere from 3-15 feet on both sides of the wire.  Shock intensity and duration is also adjustable (anywhere from a quick buzz to longer).

You should be able to make that work.  I know what you mean about small...