I wouldn't bother with beet pulp. The PITA factor for you as a boarder makes hay and a senior feed better option. You can feed her more hay if you'd like, but it doesn't really sound like you will need to. Feed her lots of good quality hay, and a good quality senior feed. You're making feeding her harder than it needs to be.

If you're told about vampires, it's a good thing to be told about stakes at the same time.- Terry Pratchett