EVO
With the weather given you could be flying into cloud at 400 feet, and "takeoff with less than 600' cloudbase is not recommended".
Actually the cloudbase
is 600' in the example. Definition of cloudbase being 'Lowest layer of cloud of BKN or greater, or first layer of cloud if nothing greater than SCT'. If the 'SCT' amount was only 3 oktas (SCT being 3 or 4) then it's quite concievable that you could avoid it quite happily.
Nothing wrong with the VFR departure as quoted and then redeclaring yourself IFR on departure. As class 'G' airspace does not require any form of IFR clearance then it's up to the pilot to fly iaw the Instrument Flight Rules, none of which require any form of ATC intervention unless requested by the pilot. It's like everything in flying - you make your own risk assesment and fly accordingly. If it was WCollins in this scenario then I don't have a problem with it knowing the man, the experience and the equipment involved, as well as the airspace. I would have quite happily done the same.