Our two rabbits have a 3 foot by 6 foot pen. I could climb in there with them, but I sense they wouldn’t like it. There outside enough that we can comb them for loose hair. They don’t seem to mind being combed. I put them on the dining room table, and I sit on the floor if I have to syringe them. With me on the floor, it’s easier for my to get the syringe in their mouth properly, which make the process easier for the rabbit also.
About the pen. We started out putting them in the pen at night or during the day when were going to be gone. Once in, we closed the door. It was a hassle getting them in the pen since they didn’t want to be forced in. One night they had a fight while locked in the pen…big commotion and tufts of hair. They are bonded sisters but like human children I’d imagine they also get unhappy with each other. So we started leaving the pen door open all day long. It’s been continually open for months. Now, with the door always open they voluntarily spend most of their time in the pen! If they spread out on the pen floor, with their back and front feet extended they are 3 feet long. Big rabbits, not the biggest, but pretty big.