Yes I’d ideally like something with a solid base so they aren’t on the floor, and I was worried cupboard wouldn’t be insulating enough for cold nights (they are great otherwise). I tried adding a towel under the box but they just end up moving it around and it gets screwed up.Thanks! It looks like they have a decent setup already.
Are you looking for a hidey area to get them off the floor as winter sets in? I see you already have a cardboard box. Those make fine hideys too. You could always add another. If it's the cold you are concerned about, some mats or fleece could be placed under (or in) the cardboard box for warmth.
If they don't use the pink carrier, then might as well remove it. I'd be concerned they could jump on top of it and then over the cage wall.
Speaking of the cage wall, a rabbit could hop over 2 grids of height pretty easily if they desired. Have they tried that yet?
Now that I see your setup, just trying to figure out what it is you are after for a hidey.
I didn’t realise they could hop over a double tier. They have both lived in their for a year and never hopped out yet (or not that I know of). Would 3 rows high be better, I have some spare pieces so I could put another row around.