[plt-scheme] Check Syntax & mangled identifiers

Hello,

In the following, is there a way to instruct Check Syntax to recognize
the #'x identifier in reference and binding position as in case 1, or
in its relation to the #'_x identifier as in case 2 ?

----
#lang scheme
(require (for-syntax scheme))

(define-for-syntax (underscore stx)
  (datum->syntax stx
                 (string->symbol
                  (format "_~a"
                          (syntax->datum stx)))))

(define-syntax (u stx)
  (syntax-case stx ()
    ((_ (name val) . body) #`(let ((#,(underscore #'name) val)) . body))
    ((_ id) (underscore #'id))))

;; case 1
(u (x 123) (u x))       

;; case 2
(let ((_x 123)) (u x))
(u (x 123) _x)
----

Cheers,
Tom