I had a picky eater before like this as well. What I did, was take some newspaper and crumple it up, scatter around the tub, (this makes them feel more secure) and do not hold the snake what so ever. Just water changing. This mojave would not eat! Could care less what it was.
He was pounding rats every 5 days before I sold him. I also tried the smaller tub, but that made it worse and he was constantly roaming/stressed out. Put him in a bigger tub and it worked. I eventually took all of the newspaper out and he was fine.
Sometimes I would have to leave the rat pup in overnight because he would not eat with any lights on. This was f/t as well, not live. It was a good 4 months of not eating.
All of this changed just from moving him to a bigger tub and using crumpled up newspaper. I read the newspaper trick on here a long time ago and decided to use it.
Cheers