yeah, if it wasn't for all those 6' weather ballons that always blow into the trash fences I might have had a better time last year.
I say keep its altitude reasonable and secure it with steel cabling or high-test rappeling rope and you should be fine. You'll probably want the main anchor for this to be an automobile or something of that integrity.
I bet 4 cars, placed in 4 corners of an imaginary square, parked about 50+ feet apart with a single cable/rope each to secure the balloon....you'd be good to go.
Also think about WHAT IF one of those guy lines were to rip off violently during one of the daily wind storms....is it going to swing around & decapitate your neighbor? You don't want to be "That Guy" who was involved in another (avoidable) playa death. Once again, keeping its altitude reasonable will allow for short rope lenght (AND better anchoring angles) & it will also keep the number of serious injuries due to massive lacerations & amputations down a bit.
I'm diggin on all this airborne art that I think we'll be treated to this year! Keep it up.