I've always just used a damp pillowcase. Since you need to bag him anyhow, get the case damp with pretty warm water since it will cool quickly. Put the snake in the pillowcase and tie the end closed. Then put it in a tub that you can close the lid on.

Move your racks, get his tub ready and when you open the pillowcase to put him back in he should have taken care of the retained shed. The friction of the cloth against his scales and the dampness of the pillowcase work wonders.