My grandmother used to make meatloaf with ground turkey breast, and it worked great. I've never tried this (and I've no idea where her recipe is) but I have seen other recipes that call for this. I don't know why ground chicken breast wouldn't work well, too. And I would guess that TVP would work well too, as long as you had some bread crumbs or egg whites or something in there to bind everything together.
I'd try taking the recipe you have and using it as is but with the turkey/chicken sub. I bet it turns out great.