A-frame box update

We've done several sessions in the living room over the last few weeks. The first part went fairly well with C&Ting for going fully in the box, then throwing the treat outside the box. Found it a bit cramped when moving to the part where I stand several feet away from the box in various positions, so we brought it outside. Outside it didn't go so well; after being released from her sitstay she would come to me instead of going to the box. I wonder if part of the problem is that my box doesn't have the riser corners so it kind of disappears in the grass. To fix that I have bought some sponges to put at the corners so it sits a bit higher up. Haven't had a chance to try it out yet.