All in all good news.
The coolant side of things is worrisome. Cooling is two things, air flow and coolant flow. You are already head and shoulders above the existing fans so it is unlikely air flow is the issue. You are also managing the onset of significant flow both for AC and low speed driving. Added to that the additional ducting to evacuate air out of the dog house.
Out of curiosity have you tried covering your new outlets out of the dog house to see if there is possibly reversion happening due to positive pressure in the wheel wells? (Which would be a real pisser)
Have you looked at the water temp into and out of the radiator?
Do you have any sense of the flow around the system? Not sure how to get a sense of this. There is a mathematical way to take the air volume, existing air temp and then the input and output temp of the piping in this case (actual temp sensors would be better) to then calculate flow. Sadly my engineering education ended well before getting into thermodynamics etc so I am of no assistance, no surprise
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Then there is the other elephant in the room which is the water pump and its ability to move coolant, restrictions upstream along with the thermostat which others have suggested alternatives to.
Painful trying to resolve cooling issues on a system where making changes are so complex due to the restrictions in the space in the engine bay and getting things around the complex geometry of the engine itself.