My perception (as I have never sought this activity) is that finding an SP who will engage in hardsports is likely to be difficult though not impossible. Finding one who will 'receive' even more so.
The other consideration is a practical one. Providing watersports, for either party, simply means increasing water intake to ensure a full bladder. Emptying your bowels to order is not that straightforward. If you are happy with the "here is one I made earlier" Blue Peter version then that is easier. This also assumes you are happy to transport it with you in your car (or the train/bus).
However if part of the fetish is that you need to do it 'live' during a specified one hour window, then that presents a significant challenge.