That might work if there is a way to also let air out while you are pumping to filter into the bladder.

If you use a pump filter with a bladder in this manner you will also be pumping air in, and it needs somewhere to escape.

Let's just say I know how really awfully strong a Platypus Big Zip is... it stretches quite a lot, and survives being blown up like a balloon to three times its size without issues. Thank goodness. Still doesn't leak, for all that torture.