Staking arrangements for STTs

[Ansky]

I am probably going to be staking a friend for the 55 turbo 1 and 2 table SnG's on stars in the near future. He can 16 table fairly easiy, and will probably play ~100 a week. The plan is to stake him for 500 sit and go's, so it should be around a month and change. Over 1200 1 and 2 table 16 turbos he has a ROI of 19%.

He is insanely overrolled for 55s but he's a huge nit w/ spending money and this is sort of a training wheels process for him.

I'm trying to figure out a plan on how to arrange this. I was thinking I'd transfer him 3000, since there is basically no chance he goes bust that way, and it seems like an adequate amount. As for profit, I was wondering what is a good breakdown. Is 50/50 a pretty standard way to do this? Or is there a standard for this at all?

Thanks in advance for replies STT.