... the issue is the way doublequotes are interpolated.

No, per tye above, the problem is with scoping within a statement:

c:\@Work\Perl\monks>perl -wMstrict -le
"my %foo = qw(do done  eggs ham  was were);
 ;;
 my @v;
 (@v = keys %foo) == 1 or warn qq{Got more than one: @v};
 print qq{V:@v};
"
Got more than one: eggs was do at -e line 1.
V:eggs was do
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