We use those large metal bins used in food service because the metal makes it so easy to clean.

Edit:

You just put the fabric between the cheeks, I don't see the problem.

It's more of a squat, hovering over the toilet seat.

Sit in a chair, rest your elbows on your knees, and lift your ass. Now, use the elbow of your non-wiping arm to keep the support while you wipe using the other arm's hand.

I have a cat that does it and we have a giant box. They sometimes see that it hasn't been scooped which is usually right when I come home from work. If an expert can chime in I would like to know which. Comfort is more logical but cats are known to be hygienic, it is perplexing, unless it is just both.