Wow, amazing responses! Thank you so much! There's a lot of questions to answer, and I'll do my best to provide all of the requested information.
Soil: I am in an Atlanta, Georgia suburb, and while the soil in our pasture is not really clay per se, it's still Georgia soil, so it's heavy. We've had a TON of rain in recent weeks, so the ground is quite wet....wetter than usual to be sure.
I am using an American FarmWorks 15 Mile controller (0.7 Output Joules, 0.9 Stored Joules) and 17ga steel wire. Plastic insulators attached to wood posts as pictured below. To eliminate possible issues with the buried insulated wire, I am stretching a length of wire across the gate from insulated post "T" to insulated post "T".
The tester I am using is NOT contact-less, it has a ground stake of it's own and a dual prong probe that straddles the wire (
https://www.tractorsupply.com/tsc/product/american-farmworks-digital-fence-line-tester?cm_vc=-10005)
Please forgive the crude sketch, it's not anywhere near scale and it's not pretty to look at, but I thought it might help visualize the setup.
I plan to make another perimeter walk listening for "arc" or "pop", thank you for that suggestion. In the meantime, I do hope this information will solicit more suggestions and feedback.