Which would you pick?
All of that is fine either way. I'm reading that as you saying you don't want to keep the loin in the smoker as long as the belly pieces, and I am assuming you want to take your loin up to 160˚. That would be fine to put the loin in the oven to finish it.
If you are taking it to 160˚, and you have enough smoke on the loin for your tastes, I would get it to 160˚ fast, because the longer you take to get there, the drier it will get. I'd set the oven for 190˚, and "Get 'er Done".
I never put water in on any of my Bacon smokes.
Like Chefrob said---fridge over night---then slicing. You'll see a big difference.
Then you should find a slicer to use, or get Chefrob up from AZ to show you some of his Ninja moves.