Not certain of county, state, city regulations. I imagine if you are talking a large gathering, say 50+ probably some kind of permit? If it's just 3 to 10, can't imagine it being a problem. Tons of shade.
It's a public area, you can check with Tonto national Forest to see if you can rent out the area for a period of time but again, it is a public area not private property or commercial area set for ceremonies or buisness.
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