Hi,
I've been into this for a while, and what I've always looked for is an oversized version of a baby diaper -- not just wider and longer, but entirely scaled up, keeping all the proportions the same.
Compared to what we currently have available, this would basically mean increased thickness (maybe like 4 bambinos) with much thicker plastic, and a high waistband (around the belly button).
As for price, this would be expensive, but I'd be willing to pay.