I am going to go with eye bolts across upper jaw inside, between rows of teeth = two one at back and front and one in lower jaw.
Pull string through top it raises jaw on bottom. Jaw returns via its own weight. A bit narrow but should work.

I drilled a hole through the lower jaw then through foam support for above the flange which the carrying pole screws into.(center bottom off skull) Through the hole I put a bolt with washers and nut.

Today I finished its mane with ribbons and bells.

Conrad