This is actual perfect timing for this question. I was just putting together a pet sitter guide for people to fill out for their rabbit sitters. When are you going on vacation? I will be putting up the guide in the next few days.
I have a pet sitter come to my home and I have also pet sit for others, and no it is not too much to ask for someone to come once or twice a day. It's best if they are rabbit savvy, but if not, then it's best to educate them on signs to watch for that mean a bunny is ill.
It's also a good idea to have a credit card on file with a local rabbit savvy vet, along with contact information as well as directions from your house, so that in the case of an emergency, the sitter can rush to the vet if need be.
If you are leaving very soon, I'll go in more detail, but if you can wait a day or so, I'll be back to post when the pet sitter guide is up.