With both Cora and Kahner I did what was posted. Smaller area and shorter duration to start. Once they got some sort of routine (ex. slept on blanket) I concidered opening up more. When I did, they ended up continuing with their routine. When I lived in a 2 floor house, upstairs all rooms were left locked. Cora had about 1000sq.ft downstairs. With Kahner, because he was an older rescue and I wasn't sure what his routine was like, if he had any separation problems etc I set up a web cam that I was able to stream to my cell phone from anywhere. Just to keep an eye on what/how he was doing.
I had a very brief period of time (after going on vacation for a week and leaving dog with parents), where Cora was grabbing shoes, chewing on them/tossing them about... this was at 2+ years old... but other than that no issues with either of them. Cora started being left uncrated at about 2 years old, Kahner about 3 weeks after I adopted him but still not while at work only on shorter trips out. He had stool problems following his antibiotics and I rather clean a smaller (crate) area if I had to which is why I waited a few weeks.
I think crates should only be used for training purposes only.
So you want to train Boaz to use a crate and never use it? What do you mean? Crates aren't cruel (unless they are used incorrectly) and they are very useful (ex. travel). Its sorta like saying that your human child is a part of your family so they don't have their own room. The smaller more confined space of a crate can be comforting to the dog. Of course being house broken and having the ability to leave the dog at home is important too. Who knows maybe he'll retreat to his crate while you're away
Make sure that he gets his walk and is tired before crating. That helps too.