Is this too complex/unnecessary for a manifold?

Going to be 1/2" CPVC. 12" square inside a 48qt Igloo Ice Cube Cooler.

I say try it. You might end up with better efficiency and less dead spots where the wort just sits.

It seems pretty uniform and like it would provide good coverage. I could also add two more cross pieces in the "Middle" above and below where it Ts with the drain line.

Here is one very similar to your drawing I made this weekend.

Too complex? I've never heard of such a thing! It looks like it would work great.

IMO it's overkill.
By the time you have the long runs spaced evenly with 1/2 the space again around the perimeter, the cross pieces and extra tee's won't do anything to help in your efficiency.
Plus depending on the material used, breaking it down for cleaning and re-assembling it would be a pain in the ass.
I have a cpvc manifold with 4 long runs, dri fit together for ease of assembly and cleaning, and regularly get between 82 and 86 percent efficiency.

Just saying

Bull

well I assume that you will have slots on the outer runs and those run will be next to the tun walls. Don't do that, it will just channel the wort down the wall and not thru the grain bed.

Batch or fly sparging? IMO, it's overkill for batch sparging as the configuration would make no difference. FSR402's suggestion is sound if fly sparging.

I think a simple "H" pattern and pulling from the center of the H would work great for fly or batch.