Maybe something simple/stupid like:

use CGI ':standard';
my $did_blank;

while (<FH>) {
   chomp;
   if ($_) {
      print Tr(td("Checkbox"), td($_));
      undef $did_blank;
   } else {
      print Tr({-bgcolor => '#006'}, td({-width=>298}, '&nbsp;') x 2)
         unless $did_blank++;
   }
}
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