The reason I ask is, conventional wisdom has been anything in the path that aids low speed air flow cooling, inhibits high speed air flow, including any fan. It would seem like your cooling issues are in "inhibiting" range. I understand car needs dual range cooling. I would have thought your what looks to be very functional spoiler/splitter would be a bigger plus in cooling then you have shared here. I personally don't think its related to air not being able to escape after exiting radiator, more not enough air getting in. You do have a lot of items in front of the hot water. Guess we can wait and see how you resolve this.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.