Great!
You might want to work a bit more meat into their diet, simply because wings do contain quite a bit of bone. I try to shoot for more of a 'prey model', meaning that when not feeding the whole animal, I take into consideration the ratio of bone to meat that would otherwise be found in the whole animal.
The easiest way to do this is just to cut up a whole chicken, rabbit, turkey, fish, whatever, and serve the parts over the course of a week. The cornish game hens should be great for this, and should be pretty balanced.
If feeding backs, wings or necks exclusively, I'll try to work an all meat meal (like ground beef, chicken or turkey) in somewhere.
I tend to gauge by stool quality. If the stools are small dried balls and whitish/yellow in color, or if they fall apart as they're coming out, there's too much bone in the diet. You need to be careful of this as it can be hard on the liver and kidneys, and it can cause constipation/impaction. Ideally, you want them to be well formed and to come out in one nice, firm connected movement that tends to be a medium brown to a dark brown, depending on what protein source you're feeding (beef tends to be darker than poultry).
Sorry! TMI and way too graphic, I'm sure! :lol: