No way is an air compressor getting the clippings out from under the shields. The clippings seriously clog up under the shield. I hear what you're saying about the water and possible damage. There are already holes in the shield, but impossible to clean without removing the shields (3 bolts)...
I have the same mower.....my problem is not buildup under the deck near blades, it is under the shields around the spindles on top of the deck. I mow at full throttle and it never seems to be an issue bogging down. It take a good 30 minutes to clean out by removing the shields and hosing down...