Zero (2w) and 3G/4G LTE Base Hat GPIO connections and antenna advice

Based on the size of the zero (2w), I’ve been using the pi as the “hat” on top of the device as follows:

I think the Rpi zero (2w) would be ideally located on top of the smaller base hat. I currently have a long and short pin length GPIO female “headers”. I’m currently placing a long GPIO female “header” on top of the base Pi Hat, which pins protrudes out the bottom (not ideal). Then I place the short header on top and “sandwich” the raspi between the “headers”. It’s not soldered. I have had trouble with a finiky connection but right now it seems to be working allright.

I think I could purchase another short pin female “header” and get by with this, getting rid of the long protruding pins underneath. But I’m interested in how folks think I should connect them.

Finally I’m looking for suggestions regarding cheaper testing antennas that support the 600mhz band 71 so I can attach and test out my portable hotspot.

I’d appreciate product advice, and links to products at resellers both.

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