With rabbits you want to simplify everything. They are not going to get the same level of care/interaction as they would if it were you, but it will be good enough for a few days. We are always getting members on here who are mad after the fact that their sitter did not do this and that and the other thing. I think that the expectation is too high. Expect them to be fed and watered. That’s it.
I would not have a sitter allow them out, too much can go wrong. Make sure their confined space is larger enough to allow exercise, maybe even adding an additional xpen. Have plenty of toys and boxes to play with.
I would not have a sitter cleaning litterboxes. Have a second clean litterbox “waiting in the wings” that can simply be swapped out with the old one halfway thru the trip. The sitter can put the dirty box in a large garbage bag for you to deal with when you return.
Make up pre-portioned amounts of safe veggies and put them in the fridge, one bag for each day. Make up ziploc bags of pre-measured pellets. This way all the sitter has to do is retrieve one bunch of veggies and give one baggie of pellets. Move the hay box next to the pen and provide a way for the sitter to just scoop more hay on top of the old.
You’re going to return to a mess, but simplifying everything is going to make it easier on the sitter, and more likely that you can go back to the same person in the future. If watching your pets is a pain in the butt, they’re not going to do it next time. I’ve gone on several trips and have learned each time to make it easier and easier.