It is hard to organize trip to L?deritz or Lapalme to make some numbers.
We have plenty of land that could serve as well in the middle of civilization and comfort.
With possibility to achieve optimal conditions 24/7/365
My most recent idea is to create ring course.
Instead of straight line that require instant acceleration and deceleration, we could inclemently increase gain speed, constantly.
Whole concept require plastic tunnel above and powerful wind turbines running on solar panel or wind turbine

So assuming that we have unlimited funds ( for example by converging rich sponsor from rugby to water sports) we could do some preliminary assessment:
-how much it may cost
-what are required dimensions
1.The first question will be:
What are parameters of our water run , for comfort and safety>
Assuming that we sail constantly on the curve , with optimal wind angle.
What will be radius for speed board at top speed max above 100kmh/h ( ?> 50 knots) to take that bend comfortably? 500M diameter or more? b) what is the width required for comfort and safety?
10? 20M ?
c) what is optimal depth? assuming that we have artificial means to extinguish all bumps and waves? I guess that for pure safety rezoning water should be deeper then 30cm required by top speed vessel
if we could make this 1m or deeper we could utilize the same channel for speed foiling.
d) the high of that tunnel? 6 is min but 8-10 or more shouldn't be more difficult.
Height is important because in our artificial green house , we need to provide laminar flow of air.
At the basis of this concept is creating wind, at almost perpendicular angle along whole ring. By series of grids- like our automatic transmission in the car.
3. Then we could calculate power requirements to artificially tumble the air inside whole channel
I guess that before we may have our ultimate 365 days speed runs, smaller version could be created around the world as recreational parks. Instead of swimming pools and stations converted to beach by electric fans ,we may have permanent installation similar concept to ski fields in the middle of desert.
Water park could be just 100 _200 meters in diameter ring covered with greenhouse plastic.
wind moderate 15-17 ktn inside.
btw. Futuristic design could involve solar chimney. In such example our wind is created by chimney and air warmed by sun.
This design could produce electric power at the price competitive to solar panels or wind turbines alone.
This design could be then easy to find a sponsor and could be self funding or even highly profitable venture.