I've had pretty decent luck with plastic-coated hardware cloth too, but your point about moisture is spot-on. A couple years back, I helped my uncle redo his basement bathroom—nothing fancy, just a DIY weekend job. We used similar stuff behind the sink area, thinking it would hold up fine. Well, fast forward about two years later, and we started noticing some rust spots creeping in around the edges. Nothing catastrophic, but enough to make me cautious.
Since then, I've been a bit more careful about sealing edges or spots where moisture might linger. A quick coat of waterproof sealant or even silicone around the edges can make a big difference. Takes maybe an extra half-hour tops, but it's worth it for peace of mind. Like you said, better safe than sorry... especially when water's involved.
Good call on the silicone sealant—it's surprising how many DIYers skip that step, thinking it's just extra hassle. I've seen similar rust issues pop up even quicker than two years, especially in bathrooms with poor ventilation. Moisture's sneaky like that... it finds every tiny gap. Spending that extra half-hour sealing edges is definitely worth it. Learned that lesson myself after redoing my parents' shower area—wish I'd been as cautious as you from the start.