Low-rider tips / help?

Hello!

I am recently caged for the first time, using some Chinese clones of Holy Trainer v2 devices (resin, closed tube type):

long @ 58 mm tube length & 34 mm diameter
short @ 48 mm tube length & 34 mm diameter
variety of base-rings (downsized to a 45 mm from a 50 mm for better / closer fit)

I have a few issues I would be pleased for some input to:

1.) For those of us with long / dangling full balls, is there some method to get the "high & tight (to the body)" device wear experience (other than the boot-lace trick)?

2.) Any tips on "loading" the closed tube, when my girth is a bit larger than the tube (flaccid diameter is ~43 mm, tube is 34 mm diameter)?

I had the best luck so far with water-based lube and "stuffing" my cock in, but the head keeps retreating over time from the end slit.
I cannot help but feel I should get more to "load in", but it will not stay in (since the device keeps sliding down to cinch my balls and dangle).

I have some examples (with the "long tube" and 50 mm base ring) in my Gallery.
I still have this issue with the "short tube" and the 45 mm base ring.

Thank you for your time and wisdom!

 

Thanks @jemima for the advice.
At first I tried with a sizing ring that matched the next base ring down (#2, 40mm), however could not "wrangle" both balls through it.

I became frustrated, but thought to try the base ring itself anyway (wider, firmer, easier to work with).
I was very surprised with the fact it fit!

Very snug, but feels "just right", with note quite a "high & tight" experience but likely the best I will get (so that's a win.)
Also did not experience any "slide down" as I had previously with the two larger rings.

Looks like problem solved!
Now will have to revisit what the proper tube to use will be, since I can now "load" more effectively (without travel).