If he's a good weight (lean but no ribs or other bones showing clearly) then I wouldn't worry. Delgado was only 67 lbs two months ago at 17 months but it's a healthy weight and I'm not going to put extra fat on him for no reason
My only concern was when you empthasized he was "REALLY lean" which lead me to believe he was underweight and you wanted to add weight for health reasons.
There's no prep needed for feeding them a little raw meat, their system should handle it fine. If I'm making dinner I just toss the dogs a piece of the meat I'm cutting up for the meal, usually chicken or beef before any spices or anything is added. With a baby around it's probably best to feed them out of their bowls and then sanitize around it, or feed them the treat outside if you're concerned. I don't feed raw meals, just for treats so it's a small amount at a time. Chicken bones are fine for the dog to chew but it does take time to chew for most so again, outside or put in a specific area is easy to contain any mess
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010