If it is listed under CITES then you won't get it in. eg Leopard and Elephant Ivory. Warthog are fine. They are simply worried about the ivory as they don't know the difference.

It is easier and cheaper to get pelts in if they have been tanned in Africa and the Taxidermy studio should be able to provide a Veterinary Certificate saying they have been tanned properly. Same with shoulder mounts if done in RSA.

I have no knowledge of wet hides.