This is not going to work out because the listing agent will attempt to take you on as a customer while simultaneously representing his or her seller (multiple representation will not apply here and he will side with his seller client)

The listing agreement between the agent and his or her client will spell out the amount of commission payable, and this will not be shared with you.

Your lawyer drafting the offer does not have fiduciary obligations in terms of your best interests in the deal.

Why not just get a Realtor who will be willing to lower his commission payable as the cooperating brokerage which is 2.5%. I have seen agents lower to 1%.