I have a little heartbeats too and like the construction. I did find that puppies chewed the upright posts but they should be easy/inexpensive to have replaced when necessary.

I have the 4x4 with the 2 ft extension and found that a 2x2 rabbit pan with equine fresh worked well for a potty box for a litter of 5. For a bigger litter you might need two pans.

I had a couple of handles put on two sides and set it on a sheet of linoleum. With the handles to lift one end tnen the other I could tuck 4x4 fleece pads under the edges. I used a 4x4 pooch pad from revival under the fleece for additional absorption. The whole system worked well for me in the space I have for an occasional litter.

If you do litters more often you might find the Jonart to be worth the extra money but for me this worked.