For completeness, I ran into the same problem, but feature refaliasing is your friend.

According to the docs it was introduced with v5.22

 
use experimental 'lexical_subs','refaliasing'; 

my sub looks_like_number;
\&looks_like_number = \&Scalar::Util::looks_like_number;
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see also my proof of concept in Re^3: Pure perl lexical sub import (POC)