Extra Heavy Load

My 7-th grader's backpack weighs almost as much as she does.

Seriously. This is insane. She has to sit down to put it on.

I am worried. 

No amount of discussion or logic reasoning have helped to convince her to unload the thing.

We argued, we fought, we tried to be as convincing as possible. There is no good reason (from parental perspective) why her backpack needs to have so much stuff - it's practically bursting at the seams. 

Here is what she throws back at us:

• Everyone else has a backpack as heavy as hers or even heavier.
• She can't leave anything at home - because she needs everything at school.
• She can't leave anything at school - because what if she needs something at home?
• There is no time to go to her locker. Therefore, even if she could leave something at school - she wouldn't do it.
• "It's my back and my health!"
• A substantial chunk of the weight is because she has to carry her chromebook with her at all times. (I don't think it weighs all that much... but convincing the 12-year old? Ha.)
• Her water bottle is heavy (really?)
• She has to carry her gym stuff with her (they have lockers! I don't know why she doesn't use them!)

I am tempted to:

1. Sabotage the backpack.
2. Sneak into her backpack at night, take stuff out, deal with consequences when she notices.
3. Hire someone to carry the backpack for her.

Here is what I probably should do:

1. Talk to pediatrician - see if they are more successful in making her see reason (and discussing potential harm of super-heavy backpacks).
2. Talk to other parents (not sure what good that would do, but couldn't hurt).
3. Keep talking to H and nagging about making the thing lighter/leaving stuff in her locker.
4. Replace her backpack with a smaller backpack that she wouldn't be able to shove as much stuff into.

Any advice???