I dont so much think that you want your sub husband to have a foot fetish as much as you would like to have your feet worshipped.

If he is the sub and you are the mistriss then why not just make him care for your feet. He is incharge of caluses bunions and the condition of your nails.
It is his responcibility to massage your feet and make them butiful.
If they are not cared for to your satisfaction then he sould be punished.
While you are at it he should also care for your hands as well.

Just a thought
Moby