I for one think this is a great idea. I would like to echo the comment regarding static caravans though. They are pretty ugly things that I wouldn't pay to spend the night in. However, proper cabins would be great.
I reckon the way to make it work is to allow the non-flying public to also rent the cabins, that way the money would keep coming in and the investment would be recouped in a sensible amount of time. You would of course need to locate the aircraft parking far enough away from the cabins that kids throwing things around wouldn't be able damage aeroplanes.
If there were then electric cars/scooters and bicycles available for a reasonable fee then I reckon that completes the picture. I would certainly fly in.
@Mike Hallam, I'll also be popping in to Sandown! I love the field and haven't dropped by since you guys took over. I applaud your can-do attitude and wish there were more people in British GA like you. If I'm not feeling flush enough to rent one of Bembridge's chalets then I'll be dropping by to camp with you.
Good luck guys, its the risk takers like you that will reap the rewards. Perhaps there are local authorities that will help you out with loans or grants if you're drawing 'wealthy aviators' to the island? (Though I'm sure you've probably explored this avenue already)