I would agree totally. But then I hauled a 5 yd loader bucket set as far forward as it could go and it still wandered around. We checked the thing for square and it was, it just wandered. Every single axle Uhaul I've ever rented for the most part did the same, though I don't think of Uhaul...
My father had a single axle 7k lb trailer built by Cross Country. I think it was around 14'. We hauled all sorts of small tractors, farm implements and a mustang once. He wanted a single axle to get lower toll rates on the thruway. I couldn't stand that trailer- no matter how it was loaded...
I have a Delta 6x48 with a 12" disc that I would part with since I got the 2 x 60. It's in the Cleveland area, not sure OP wants to travel that far though.
You can use something like this-
https://www.grainger.com/product/39RJ30?gucid=N:N:FPL:Free:GGL:CSM-1946:tew63h3:20501231&gStoreCode=161&gQT=1
Edit- Link title doesn't work, but link does..
ADB HOIST RINGS Hoist Ring: Pivot/Swivel, Alloy Steel, Screw-On, 4,000 lb Working Load Limit, Black
And here are links to the parts I used:
Jack mount, $10 ea:
https://www.amazon.com/dp/B004QEM7QG?tag=atomicindus08-20
Jack is $95:
https://www.amazon.com/dp/B004VRT3Q0?tag=atomicindus08-20
Here is what I did. This was primarily to stabilize the end of the trailer when loading/unloading a 12k lb skidsteer. But between the two rear jacks and the tongue jack, I can lift the entire trailer off the the ground if I wanted to. And the two rear jacks are removable so they don't rust or...
If it was me, I would take those supplied nuts and drill right down through them removing the threads.
Then I would lay them out and give them a shot of paint on both sides, this is to help slow galvanic corrosion.
Then use 316 stainless bolts and conventional nuts (or nylocks if you really want...