Has anyone used one of the Solio solar charges in an area that is mostly overcast? Myself and 4 friends are going to be paddling up the inside passage for 5 weeks in June and July and we would like to bring a solar charger to charge the VHF radios and a video camera. Has anyone used it in a clear dry bag? Have an idea about how fast is charges under overcast conditions? I am looking at buying the Solio Mag and putting it in a clear dry bag as it is much cheaper than using a waterproof brunton roll.