Stacking Question

I’m a new WSM owner with expansion racks question. Please forgive me if this has been addressed before.
How many racks can you stack before the smoker would stop cooking evenly and maintain a good temp?
I was able to stack 5 racks so far. I have about 2.5” clearance between each rack. I intend to use them for smoked chicken wings and sausages, so clearance is not an issue here, they’ll be great for ribs as well.
Thumbnails of the racks (click to enlarge):
Here are the racks used

2 Racks on top of the lower rack

And one rack on top of the top rack
Thank you

Are those BGE racks? They look like they have more suppot than mine. Where did you find those?

I had these rectangular racks that I used on my Char-Griller (bought them at Target), and I jus took the legs off of them and put them on old racks left from my previous electric water smoker.