not too sure I can answer personally but from what I have read:
yes it is viable and to start you would want to get a 2nd box set up by where you would want it to go (or let her decide where it should go) then let her explore it and put some of her poop in there. I f she still doesn’t go in there then try to have food in there so then when she eats in there she also ends up going in there. it seems to be just like regular litter box training but further away from her cage

Puck has two litterboxes; one in his cage, and one for when he’s roaming around outside (that might be in his pen if we’ve not Puck-proofed the living room, or at the other side of the living room if it’s been temporarily bunny proofed so that he can come out) and we haven’t had any problems. Both litterboxes are the same now, but we didn’t have a problem when we had two different types either. I suppose it depends on how your bunny is about where her box is; I believe some like to tell you where their litterbox should be, Puck’s always been happy with where we’ve put it – worst he’s ever done – since being neutered – is rotate it a quarter turn when he felt like a change of view Even when he did that, he did it so neatly I thought my SO had done it XD But Puck seems to be quite big on rearranging his living space.
Not knowing your bunny, I can’t say for sure, but when I introduced a second litter box, I set it up the same as the first one, put it down where I thought he would be mostly likely to want it, and just kept an eye on him to make sure he didn’t decide he wanted to do his business someplace else. I also put down some sheets and left over vinyl flooring to protect the carpet because I’m neurotic, the carpet is new and we’re in a rented flat, but if your bunny is very good about using her tray, you might not need to, or might only need to for the first day.
I think I’m rambling now, so I’ll shut up. Hope that made sense, but if you need me to clarify, let me know