I like to stuff minced onions and shallots under the skin prior to roasting. Does this method weaken or dry the skin too much to do that? Will it be prone to tearing? thanks.
No, it'll still be sturdy enough for poking around!
The texture of a turkey's or chicken's skin has more to do with how the bird was raised than what you do to it prior to roasting. If the skin seems like it can handle a few onions and shallots, I'd say go with your usual method.