Aftermarket defroster?

Has anybody tried installing something like:
https://www.frostfighter.com/clear-view-defrosters-about.htm
for the rear glass on their canopy?

I'm mainly concerned apply heat to the glass might shatter it, although 50F is probably not enough.

 

Here's the link for their line of defrost for shells:
https://www.frostfighter.com/pickup-truck-rear-cap-topper-window-defrosters.htm

I can't imagine they'd crack the glass any more than a factory setup would. It's not like you hit the button and they're instantly hot, they take a little to warm up. I found a couple of reviews online including:
http://www.gmtruckclub.com/forum/threads/added-a-rear-defoster-to-the-cap.963666/

I've used their products to fix the rear defrosters on a couple of VW buses and they worked fine, I've never done an install though. On my last Tacoma I used one of those water repellent products like Rain-X on the back window to help keep it clear and make it easier to clean. It may have helped a bit with ice but honestly I can't recall.

 

I live in the rainy northwest so I always have a good coat of Rain-X going. Doesn't help with the occasional frost we get. Usually not a big issue but thought for $100 I can make the problem go away.