short of a new radiator... all you can do is jet wash the rad out after playing.
but that doesnt help you get home afterwards!!
with the rad having 3 rows of fins on the cores, the inner layer seem to corrode quicker than the outer layers.
hence the heat is not disapated as efficiently, ergoe, overheating.
i had the same problem for a while, a slight incline on the motorway and i was getting rather warm.
a new radiator has solved the problem, 100%.
hope this helps.