Very nice! I'm glad there's another person around who can make tanks work!

Try aspen for substrate. It's not as messy as ecoearth or as prone to bacteria. Looks nice as well.

And as to FT switch over - as was said it's all up to the individual snake. I have two adult BPs who refuse to take FT no matter what I try...but they love PK. On the other hand, my biggest adult female (a rescue from a clueless fool) took to FT the very first time I offered it to her. Same with my spider girl...but then, she's a pig.
Just be patient and consistent. Only offer the food you want them to have, in this case FT, and if they don't take it they wait another week. Don't give in and feed them live... they can go a long time without food if they must.

Keep up the good tank work!