credits toward principle on a lease option

[Michael Campbell]

I am trying to work a lease option deal where the tenant buyer gets $200 a month out of their monthly rent to go toward the purchase price of the home once they exercise the option. I have heard that a rent credit can only be fulfilled in the form of a seller concession and not to exceed 6%. However, there is already going to be a seller concession in the amount of $2500, so that the total credits to the buyer when including the $200 a month for a 2 year term would exceed 6%. 

The purchase price of the house is 220k with the monthly rent at $1500 and a $10k Option Fee being put down. 

I am wondering if I can increase the amount of the non refundable Earnest Money (option fee) by the total of $200 x 24 (months) making it a total of $14,800. $10k would be put down up front and the remaining amount would be paid in monthly installments. If the tenant buyer exercised the option to buy before 24 months was up, then the remaining amount due on the earnest money would become part of the total amount due for the purchase of the house. Technically I would be decreasing the rent amount by that $200 and the earnest money would be paid monthly with a separate check.

Assuming that there were copies made of all the checks that were going toward that earnest money (including the 10k up front and the $200 a month), is a lender going to be able to look at that and acknowledge it as having been paid and sufficing for down payment on a $220k purchase? 

Can you see any problems with this scenario? 

Thanks in advance