Getting hot on the highway with the AC on.

What I was trying to see is, is the shroud blocking air flow at speed, does not look like it.

I think you are over thinking the temp rise.

Only way you will know is to get out on the open road at speed for an extended time (no stop and go) with ac on them with ac off. And note:

if the temp keeps rising with ac on.
What temp levels out to with ac on and off.