For an illustration (photo) of Spreading (Diaper) Pants check out this seller and his ebay listings:
Seller: pipineni (657 )
Listing: Adult Baby Thick PVC Spreading diaper Rubber lockable (131089190049)
If this does not result in the pronounced diaper waddle I don't know what else would !
Enjoy your 'Baby Elephant Walk' in the park - aren't you something !!!