Two things I notice right away...
1.)He’s older and use to eating live not f/t. Older BPs are very set in their ways and take considerably more time to adapt.
2.)Sounds like you have changed his enclosure quite a bit even though you are working to make it more BP friendly.
I would be be willing to bet he won’t take f/t in a week. My recommendation and what seems to be the general consensus is to not change their environmental situations drastically and it seems like that is occurring here.
Good luck.