20 degree split on any heater, regardless of heat exchanger size, means insufficient flow through the heater. This can lead to premature damage. Other areas of concern if this is a heat pump is the evaporator coil. Any blockage around the coil will cause inefficiencies and higher temp splits.

splitting the tri-sensor from the manifold....hmmm too risky. All you need is for the cell to be scaled and the tri-sensor to not detect this condition (blockage of flow) and you can have a read disaster. "Don't do it" is my 2 cents, besides, it voids warranty.