This is the exercise pen I have now, costs less than $40!
When I kept Thor in here, it worked really well to keep her contained and provided lots of room for toys and a litter box. I really think this is the minimum size that rabbits should have for their home area, to be humane they should be able to take several hops and be able to stand up fully on their hind legs. Rabbits don't need designated rabbit cages, they can live in many other safe environments!
I'm putting a link here to the BB page for suggested rabbit habitats:
There are lots of ways to do it and you will find your rabbit is much happier and more interactive when they have more room
My bun doesn't even have a cage anymore, she is free roam in our apartment. This is not possible for all rabbits, it depends on how destructive they are, but you can try giving her out of cage time to interact with you in a bunny-proofed room (no exposed wires or dangerous items). It is a lot of fun living in the same space as your rabbit
Edit: Just re-read your post that Clementine is only 5 months old. If she is not spayed yet, litter training may be a bit more difficult, so you would want to watch out for that if you let her out in a larger space. Almost all rabbits can be very well litter trained once they are fixed, and many do well before that as well!