Invested GC partner, profit share between flip and BRRRR

We have been financing properties and getting involved a  little bit with the buying and rehab process, but our contractor is the main on that (Finding, buying, rehabbing and selling).  We have been doing a 50/50 split on profit of the flips.

 Our newest property can be rented as a duplex, so we are looking at that method.  We are trying to brainstorm a payment method for that.  Has anyone ran into this situation before or have any suggestions. The only thing I could think of would be to pay half the difference between the refinanced amount - total project cost (purchase, rehab, fees, etc).