I don't think you are understanding the question at hand. Read the thread over again... for a VFR operation there is no requirement to have a reported visibility or ceiling. There is no requirement to have weather reporting, period. The pilot is allowed to use his or her own observations, or those of another person considered competent (i.e. another commercial pilot or dispatcher or trained weather observer) PROVIDED that there is no official weather report. If the weather is being *reported* below the visibility minimums (i.e. by a certified AWOS system), then that becomes controlling even for part 91 operations and this has been *definitively* answered by an FAA legal opinion.

http://www.faa.gov/about/office_org/...rpretation.pdf

In the original poster's question, he said the visibility was greater than 10 miles (legal for VFR) but the ceiling was reported at 300' and he specified controlled airspace. In this case, the field would be considered IFR because the ceiling is less than 1000' (91.155(c)). He then revised his question for an uncontrolled (class G) airspace, where there is no specific regulatory ceiling requirement but one must remain clear of clouds, and it would be illegal to operate below 500' unless taking off or landing. I don't know that this question has been definitively answered, but I suspect such an operation could technically be legal but would place the operator in a good position to get some unwanted FAA attention.