Transmission Cooler Inquiry

Don’t think i’ve towed since pinning it but with all the shit on my truck (skids, sliders, heavier tires, fiberglass shell, rtt) it’s like im hauling a full bed all the time.
Before i pinned it my trans temp in summer was 180-206F

 

Next summer I'm gonna do it. Not towing much of anything right now but I'd like to see lower temps even unloaded.

 

This is my pick for the best cooler currently. I'm running one for the trans, about to install another for the PS. No fancy brackets here just used the stock mounting bits and pieces. Took some work but got it done.

https://amzn.to/3MBTUU5

 

I'm still concerned about installing a new cooler and having air trapped inside the cooler.
Years ago, I laid my Harley oil cooler on the ground with the lines attached and pointing up toward the engine.
This flushed all air bubbles out of the cooler.

I'm curious if this approach can be done for a Tacoma cooler, seeing as how much body parts are in the way of doing it the Harley way.