Hi Mike,
Well done on your Euro success. For the beach I go back to stainless bearings as supplied by blokart or the cheap equivalent and make sure seals are tight. Always get a bit of sand and water after 2–3 hrs but this cleans out easily for next time. Last time I'd left in the $2 bearings used at the NZ Open so just chucked these as they seized up quickly after I had finished.
Some seals seem better than others and have found the ones from blokart pretty good. Others may have suggestions on different seal types. Regards
Russell