I think part of the problem

I think part of the problem is that the PSU is pulling air out of the case so there isn’t any pressure build up. If you have a 120MM PSU, it might be worth a shot to install that w/ the fan facing down then use both 80mm as intakes. This should cause air to exhaust out the vents over the CPU. If that doesn’t help you could also try pulling out the PCIe shield next to the card so air has an easy place to exit the case.

Another option is to build a PCIe slot cooler (I’m not aware of any low profile one you can buy). The easiest way to do that is to cut a 60mm hole in some cardboard and screw a fan to it, then use some double sided foam tape to attach it to a PCIe bracket and aim it at the tuner.