Quick-to-the-money tournament structure

[Quercus]

Assume you wanted to create a tournament that would eliminate 85% of the field within the first 20 hands dealt.

Assume no blinds during the first 20 hands (though there is a moving dealer button.) You must bet nothing or all your chips on each hand dealt. You must go all-in a certain number of times during those first 20 hands.

Is there a formula relating the number of entrants and number of forced all-ins required? (3 of the 20 hands? 5? 7?)

After the 20 hands are done, the remaining players are declared "in the money" and paid in the normal tournament payment pyramid. Blinds begin at the level normally associated with "in the money" for a field of this tournaments size.

For a good player over a large sample size, would you expect this structure to make a significant difference in their ROI?

Is this the right forum for this question?