Duct tape is made for duct work, duct also gets hot, kind I get from work is good up to 200 degrees, Id say its made for the job. Also Id rather use something non conductive vs the conductive aluminium tape everyone likes to use, on laminated 120 volt circuit.
Just book shelves with heat tape, nothing to it
I'm actually quite the opposite, I don't like the thinner material plastic racks personally, so I stick with melamine.