Issues with a Cage Padlock?

I’m running into a minor problem I could use some help with (a link would be appreciated).

My cage uses an external padlock rather than the built-in locking mechanism common to many devices. It’s quite compact, under an inch in length, and urine occasionally seeps into the lock area. This often leads to corrosion; I’ve already replaced one lock because of it. I try to manage the rust by keeping things clean and applying WD-40 regularly, but lubricating while away from home isn’t always easy. Does anyone know a stainless steel padlock that works well with these cages? Other recommendations are welcome as well.

Thanks! Eddie