The problem is, if they know that you're streaming, they can do the same thing already. With a half-hour delay, you aren't going to be able to interact with chat anyway. It really sounds like you should just record, then upload the recorded video.
Ah, HoN. I gave them money at one point.
But when the Devs jumped in on being outright toxic to their top players, you knew the game was going down fast.
But yeah, no. 30 minutes is the maximum stream delay in OBS, and there's no way to extend it further. Sorry, man!