I haven’t needed a custom order, but I have ordered 4 sizes over time. If your head is not sliding back inside the innerwear when turtling, you might be able to order a smaller diameter sleeve. The sleeves really help prevent the innerwear from bunching up. If your head stays in front of the ring, that might help. You could also test wrapping some athletic tape around the innerwear to keep it extended.
I have a smaller diameter premium sleeve that works great, but it is pretty hard for me to put on! That matches a smaller and longer innerwear that I must turn inside out to put the ring over my head first, then work to pull the innerwear on where it should be. Fits great for days once on, but it is a struggle when too tight.
