kite surfing sounds so limiting on such a unique site... I'd think 5 days/week would be raining there so kite suring would not work and why would anyone go there to kite surf.  We'd just do that in our backyards until we got bored.

I suggesting operating on the natural features of the site... Perhaps make it into a sanctuary of sort, with artificial lakes, marshlands, hills, bird/animal sanctuaries - a place where people could come for a mini holiday and enjoy nature in all its glory, take part in nature activities, away from city life.

Or you could turn it into a culinary center perhaps, where people could enroll in day courses or extended study in the culinary arts and it would be a self sustaining school with the students growing their own food in gardens, orchards, fisheries etc and cooking with it.  It could help generate a local economy.  Locals could come stay as visitors and enjoy the landscape, eat in restaurants that offer food cooked by culinary students etc.  Produce could be sold to nearby markets etc.

Based on the video, you should definitely incorporate the history of the site. It has an extremely interesting and important background, it wouldn't make sense to ignore that. It doesn't have to be the only program, but perhaps dedicate one section as a museum. 

As far as a testing function and fleshing out the project goes, maybe come up with a hypothetical flight testing academy that builds planes and things that rely on the wind and human power rather than engines. Take the historical use of the site and modernize it.

Good luck!

Nuclear waste dump. Or maybe a battery production facility for hybrid cars. Same difference.