Hello All, I have a 1998 Fleetwood Pace Arrow Vision motorhome with a 'rubber' roof, which is speckled with black / gray spots that look like mold. My hope is to kill whatever is causing the spots, and to coat the roof with some kind of rubber roof-renew product. For those of you who have dealt with this same issue, what did you do and which products do you recommend? Thanks very much.