yes you can do the approach. remember you are a weather person also. You have established ceiling and visibility, all you need are the winds. Over fly the field and now you have those. For dispatching purposes you have to have a FAA approved weather reporting source. Once up in the air its up to the PIC to make the decision as to if the approach should be made or not. Its like if the visibility starts reporting 1/8 a mile AFTER you pass the final approach fix and its a cat 1 approach. If once you get down there and you see the runway you can land. you just created your own visibility report for yourself and it was good enough to continue and land.