(defun kth-to-last-recursive (l k)
  (let ((i 0))
    (labels ((helper (l)
               (unless (null l)
                 (let ((head (helper (rest l))))
                   (incf i)
                   (if (= i k)
                       ;; how to return this and be done with recursion?
                       (car l)
                       head)))))
      (helper l))))
(= 5 (kth-to-last-recursive '(1 2 3 4 5) 1))