i skin a lot of wild hogs. Never had a problem with the "shield". My method:
1. Do not field dress the hog prior to skinning.
2. Hang the hog head down from a gambrel.
3. Cut the head and forelegs off.
4. Skin out the rear legs and butt.
5. Slit the skin in front and down the back.
6. Pull the skin off. The "shield" comes off with the skin.
7. Field dress the hog.
A pair of skinning pliers makes it easy:
http://www.sportsmansguide.com/produ...-tool?a=686993