If he's in shed, that may be why he's not eating now.
As far as where to feed, I would say keep feeding him in his enclosure. I'm not a fan of special feeding tubs, but they work for some people.
I have one who used to initially hide when food was put in the enclosure. I know everyone says you need to actively monitor your snake if you're feeding live, but I don't see a mouse hopper posing much threat. She would not come out initially, but when I closed up the tub, gave her some privacy and came back an hour or so later, the mouse was gone. Incidentally, this one eats FT now, but will only do it in the middle of the night when no one is watching. Some snakes just like private dining it seems.