first heat. Leave with 2 house visits, no one overnight?

Question
Have 2 labs, the younger is beginning her first heat and wearing diapers. we were planning to be out of town but our sitter is booked for overnights and can only come by for 2 house visits during the day to let them out in our spacious fenced yard, and walk them, and spend some time with them, but she is very good. My question is, can we still take this trip?  They are used to being in the house, but no one will be with them except for pet sitter's two visits. She will be five houses away overnight sitting our neighbors' dogs.


Answer
Just how good is your sitter?  How high is your fence?  In another question here, somebody said their dog was impregnated inside their 6' fence.  Can the sitter keep your dog from bounding over the fence?  Never underestimate the efforts of a female in heat and a male to get together.  Once loose, there are far worse things that can happen besides accidently getting bred.  With her being in heat added to the sudden loss of company, I am not sure what might happen.  Have you gone through having a female in heat before?  

I really think everybody would be better off if you had spayed her a mounth ago.  We have no desperate need for more people to be breeding.