I could see the thought of the bumpers being a waste with bedding but i assure you it is not i use 2 inch PVC pipe mounted with PVC straps in my whelping box

Also i bulit in a double pane plexy glass viewing window to be able to check on the gyp and pups without disturbing them box is insulated with bulit in heat lamp and fan both controlled by dimmer switches just some food for thought

RoughNeck