I haven't done stuffed breasts in bulk before - only in relatively small portions, using my air fryer. But I've had success with using cream cheese, mixed with garlic and herbs, then wrapped in parma ham. A friend does something similar but she uses deboned thigh fillets and then also makes some kind of white win sauce to go with it? I'm not sure as I've never made a white wine sauce in my life, but it always tastes good and she whips it out for dinner parties.
For chicken tray bake, our favourite is a slower cooked one. So bone in, skin on thighs, but nicely trimmed. Then in a big roasting tray that will fit all the chicken pieces relatively snugly mix up olive oil, lemon juice and a generous tablespoon (or two) of whisky or brandy. Add a couple of chopped garlic cloves, then some cumin, cinnamon and a tiny bit of ground coriander. I like to add fennel seeds although I think that's my own addition, not from the original recipe! Marinade for a bit if you have time (I almost never do) then ensure the skin is facing up on all the pieces and sprinkle generously with salt.
Put in a relatively low oven - 150 fan or so - and cook for about 45 minutes. Baste the chicken and back in the oven for another 20 minutes. You can use some of the juices as a sauce (or turn it into gravy if you are feeding a child like DD who thinks gravy should go with everything).
The nice thing about this one is that because it's relatively low temp, it doesn't really matter a lot if you cook for a few minutes more or less which I find handy when doing it in large amounts because I have guests over.
I usually do this one with mash potato, but I think potato dauphinoise would also work.