How about trying a drop-thru style litter box? If you have those cheapy variety stores around, sometimes you can find products like Ive shown in pics below. They are tiered shelf units. I’m always on the lookout so I had some of these pics on my phone.
The baskets have a good size hole in base for bunny poop to mostly fall through, but the flat plastic shouldn’t be to harsh on bunny feet. You could look around for a single basket instead but I think these units would be handy as you can pop a clean basket in while taking out the soiled to clean. And a couple spare for when/if the 1st ones you use get too cruddy. Then it’s just a matter of finding a tub you can sit the basket in. Often, these stores will have something suitable. Ideally, you’d want something slightly deeper so there is a space between the base of the basket and the tub/box. Enough for poos to fall through to litter underneath.



Close up of the holes in base.
My single bun has a large version of this. It was a tiered unit from a store that was closing down. Most of it was missing. I only needed the solid base and one of the shelves anyway so it was a good score.
He tends to poop all in one corner, so I cut out a portion of the plastic grid in that corner. It’s much larger then he needs but I originally bought it for my pair.

There are also some litterboxes around with a grid top. Kmart has these at the moment.

I have made screens with galv mesh too. They tend to break down after a while and need replacing. You’ll need the small mesh that is easy to bend. Some places call it hardware cloth.. Bunnings might have it. Also, some garden centres or small hardware stores might stock it. I cut pieces slightly larger then the box then folded each edge over a few cm. Pretty crude job really..
Just found this photo from a few years ago of one I made, slightly different style. It doesn’t rest on the litter, it’s bent in a shoe box lid shape so it sits above the litter. I don’t know if that would put pressure on the feet though. The mesh is still pretty flexible but it’s not the same as lying the screen right on the litter so it’s not really weight bearing.
