I ran into a similar issue when I tried to crunch the numbers. Basically I had to do an analysis assuming they paid as normal because I needed to find out how much of a balance was required come the January analysis. That created a headache because, in the end, they end up making nearly the same payments as before.
Another problem I ran into is that you cannot have greater than 2x cushion. But if you hold off escrows until a certain date, to make payments once you know prepayments have no longer been made, you always have more than 2x at one point. Additionally, every time you change the payment amount, it effects your beginning balance. Both numbers are on opposite sides of the equation. To sum this long explanation up, I could not get it to work.