Sometimes when we ask for help, we have a predesigned response in mind -- that is not always going to be what we get. Most reading your initial post got the same impression. So, maybe you worded the post in a way we got the impression you were crating too long, not giving enough attention, and maybe not really "liking" your pup. You have since posted that maybe that is not the case.
I do think you are looking to others to solve your problem. We can only give suggestions. The books and research you have done should have given you ample methods to try. So what is missing? I know you won't want to hear this but I think it is "attitude." The attitude you have shown to people who have given honest opinions may be seeping into the way you treat your puppy. No method will work on a puppy if you are giving off negative feelings. The puppy wants to be loved. He will be anxious if he does not get the feeling he is not only safe but also truly cared about. Just as a child may act out if there are emotional problems, a puppy will as well. Just try not to always blame others for the results you are getting.
Yorkies are not inanimate accessories that you can always set aside when inconvenient to you. They are very demanding and need constant reassurance that you love them as much as they love you. They are very different from some of the other breeds that can be more independent. They crave constant attention and interaction. I did not crate train any of mine. But I feel, once they are housetrained, they should not be made to go in their crate when you are home.
At this age, I would think your puppy should be more than old enough to be out and about in the house with you during the day. If you iron, why could the dog not be out? If he does try messing with the cords, teach him not to. Most of your home should be child-proof/puppy-proof anyway. So, give him some leeway to explore and really be a family member and not a stage prop you bring out when you think it is right for the scene you want to set. Instead of banning him to a crate while you eat, why not just train him not to beg at the table?
Advice does not always come sugarcoated. That does not mean it is not heart-felt. I sincerely hope you bond with your puppy, truly start liking him and enjoy his presence as part of the family. But if we all say you are doing everything right -- how is that helping? Obviously what you are doing is not working, so it is time to try something different. I had to change paths many times with mine. Each was different but all required a LOT of loving interaction.
How about getting the x-pen for when you have to be gone. How about giving your pup a few rooms that he can freely roam when you are home? When he chews something up (which he probably will) tell him "no" firmly, and redirect him to something appropriate to chew on. Be careful using books or advice as an absolute solution for every dog. I am sure you read some child-rearing books too. Did all of those fit each of your human kids? I know they did not for me. I had 3 boys and every one was unique as can be. A cookie-cutter approach just does not work for any with a personality of their own. Try not to demand so much of your pup or those posting to you. It is not the responsibility of others to come up with the perfect solution, just suggestions if they desire to reply. When you ask a question, be ready for some to say what you are doing is wrong. Be open to the idea that at least a big part of the problem may be yours. Then when you change how you feel about the puppy, how you change your approach to him and the way you treat him, be prepared for some fantastic love in return!
Unconditional love is a wonderful thing to know! Sometimes my Yorkies are a lot more like people than dogs -- that is one of the many things I love about them! Sometimes I act more like a dog than a person and they seem to love that about me too.
So don't be afraid to get down on the floor and really PLAY with him. Wear him out with fetch and play that gets him excited and really having FUN! Buy him more toys. By 7 months he really should have more than one monkey, a blanket and a broken alarm clock. Choose interactive toys that either will engage him (like the Hide-A-Squirrel) or that require interaction with you, like a ball to throw. Then buy some that will just be comforting and reassuring like the plush animals. If your children are old enough, show them how to safely play with the puppy and make sure each of them spends a little time one-on-one with him each day too. A puppy that is getting plenty of attention, stimulation, and love will usually be easier to train and have less anxiety. Right now I get the feeling he is not getting enough of you all and the idea of losing what little he has is overwhelming to him; hence the separation anxiety.
I may have not hit on anything you can use, but hopefully you will know that it is offered with good intentions. I think since you have done so much research, have so much input, the real solution will come from within. It will be more a question of
how you do the things you do, than what you do. I do think if you treat your puppy differently you will get different results. I once read that craziness is expecting different results while doing the same thing over and over. (This made a point with me!) So, why not try something new today! Good luck!