Splitting with back bettor, how significantly larger should the back bet be??

First I want to thank the wizard for creating such an informative website. I have used lots of your information for my black jack play and I would like to show you my entire respect for all the time and efforts you have contributed.

I have a question here concerning the unselfish acting player splitting strategy.
Lets say I have a friend that plays black jack with me and we play with the same bankroll. Suppose he splits accordingly to the second table showing here http://wizardofodds.com/blackjack/appendix19.html, I can gain an advantage of .20%.
But if we are using the same bankroll, the player in front will get a higher house edge because he is not splitting accordingly with basic strategy. In return of a higher house edge for the front bettor, the back bettor lower his house edge. My question is how many times larger should the back bet be to make this strategy profitable. For example, if my friend in front plays a 100$, what should be my bet at the back to make the strategy profitable playing with the same bankroll.

Thanks in advance for your help and answers!

LKS