Location of MLT manifold line to output

Building a manifold for a rectangular cooler MLT with several tubes running the long-way. Wondering if there's an ideal tube location to attach the output? On the line closest to the output valve? 1 or 2 levels farther from it? The line on the back of the cooler? Does it matter? Basically the concept below. Thanks!!
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If it is completely level the output location shouldn't matter much. If there is even the slightest pitch to it you would want it at the lowest spot

 

The output would be about 1/2" above the top of the tubes, when sitting completely flat. So the manifold itself should sit completely flat, but would need to pitch the outflow tube up to meet the valve assembly. Thoughts?

 

Pumped or relying on gravity, either way with sufficient tubing on the drain valve outlet it'll suck up whatever reaches the manifold - until it starts sucking air. The centerline of the ball valves on my kettles are at least a couple/few inches above the kettle bottoms but their dip tubes reach all the way down and siphoning/pumping does the rest.

And kudos for the ascii art.
It made me realize how long it's been since saw any...

Cheers!