First, the pic of her in the too big (for now) vest is adorable!!
but I'm aware that extra weight isn't good for the breed,
I think that the issue with the added weight is related to her age. Once she is fully grown (12-18 months?) she should be able to carry some supplies: a baggy of kibble, a typical water bottle.... Things you might want on hand if you were going to go for a hike in the woods. Just let her grow up a bit first so that her muscles and bones are strong enough.