Found a guy who will make custom bags- he's quoted me $35 plus $5 shipping for a set like saddlebags that will drape over the CB trunk. Currently thinking about 12 inches wide, 8 inches tall, shaped like an expanding envelope, opening to 4-5 inches at the top. sunbrella-like cloth for the inside, outside of the pocket made of philtrex cloth. He thinks he can ship within 2 days of processing the order.
Only other things I've seen have been $40 single bags at West Marine with suction cups that could be removed and strung together.
If other people are interested in something similar, maybe a volume discount could be had. I have to go out to the boat and get more precise measurements for him, but would anyone else be interested?