Glad to see your changing axle. This whole drop axle flipped upside down thing is a little sketchy to me when it comes to a trailer that will be loaded.
Having a drop on the axle that extends down from center is no less stable or prone to breaking, then if the off set was above the axle's center. Go look under any toy hauler style camper and you will see that they use drop axles with the offset below the axle. The main reason for the axle swap is to allow me to run the same tires and rims as the Tacoma.
The stock trailer tires are 27" and need to be at 50psi to carry the weight because they are so narrow. That means they are very bouncy and prone to damage on the trail. With 32/33" truck tires I can air down and avoid that same damage. I will be taking 2" out of the suspension, but adding 2 to 3" with the tire. Shocks to damping the bounce which help too.
I have already test towed the trailer behind the truck and it is very stable even at 60 to 65 on the highway.
I will likely go with a Luenette ring( the hoop that goes on the trailer) and pintle hook on truck. I can get a ring that will turn 360° on it's axis so if you flipped the trailer or the truck you don't pull the other unit over with you. The ring is rated at 17,000# for trailer weight and 1'700# on the hitch...it may be strong enough.
The hook and ring is good because I can get parts anywhere.