I am considering a date with a provider who only does outcall. I will get a hotel room for the date. But I am concerned about preserving my anonymity.  I am looking for tips from more experienced mongers about safety measures I should take just in case my provider is inclined to snoop.

There's no obvious reason why you're more vulnerable one way or the other. The vulnerability lies in whatever info you give up during screening and that's not outcall vs. incall dependent. The only thing she needs to know is your room #. You don't even need to book the room in your own name.

visiting HER hotel room incall than having her come to mine.  Get a room with a hotel safe in the closet and throw all your ID, cash (except what you need for her) and credit cards in there.  Problem solved.  The hotel will not give tell her anything about you  Even if she asked who is in room 305, the hotel will answer with, "who were you looking for?" and if she doesn't know your last name, it's a Mexican standoff and she gets nothing from them,   (This is why for me, it's first names only).  Now, if you are using Motel 6 or Days Inn, you can't count on that level of discretion from the staff.  If you choose a four- or five-star premium brand from a chain operation like Hilton or Marriot (I learned two weeks ago when meeting a provider at the Ritz-Carlton in LA that they are owned by Marriott), you will find that the staff will do what they can to protect your privacy.  You don't get that if you are a visitor going to HER room.  

Agree, but I wouldn’t even give out my room number.  I’d meet her in the bar or lobby or somewhere else. If you give her your room number you invite the risk of a ‘guest’ showing up during the date.