That settles it.
I need to wear a lab coat (and shoes!) when I brew.
My HERMS coil is 25' and it's long enough. That doesn't mean 50' is too long, though! It's just that I used an old immersion chiller which happened to be 25'. It takes up quite a bit of room in the HLT, so I'm not sure how well a 50' coil would fit. Others who have a longer HEX could tell you for sure.