I have a solution...
The OP begins to call, email, etc. The Niece every other day asking for this, that, and the other thing. Demanding that she swear a blood oath to follow the will's provisions. Inferring that The Niece and her family are guilty until proven innocent.
Sooner or later, it will dawn on The Niece that administering the estate is going to involve a constant barrage of "inquiries" from a certain beneficiary. And maybe she will finally say:
"You know, Art. I was prepared to administer the estate and do it without requesting any of the compensation that would normally be permitted. But I can see that doing so will be a major PITA. So, I tell you what... When the time comes, I will decline to serve and you can come up here and petition the court to be named as the administrator. Just don't ask me for any help. I'm sure that you will enjoy all the time that you have to spend here attending to estate maters. Or the amount you will have to pay an attorney to do so. It really is lovely country up here."