How can I append hidden input to this file input after jquery simpleUpload success?

Trying to append a hidden form field after the file input that was used to upload a file within the simpleUpload call.

So far I have tried:

$(document).on('change', '.upfile', function(){
    var obj = $(this);
    $(this).simpleUpload("/upload.php", {
        start: function(file){ console.log("upload started"); },
        progress: function(progress){ console.log("upload progress: " + Math.round(progress) + "%"); },
        success: function(data){
            $(obj).append('<input type="text" name="images[]" value="'+data.message+'">');
            console.log("upload successful!");
            console.log(data);
        },
        error: function(error){ console.log("upload error: " + error.name + ": " + error.message); }
    });
});

$(document).on('change', '.upfile', function(){
    var obj = this;
    $(this).simpleUpload("/upload.php", {
        start: function(file){ console.log("upload started"); },
        progress: function(progress){ console.log("upload progress: " + Math.round(progress) + "%"); },
        success: function(data){
            $(obj).append('<input type="text" name="images[]" value="'+data.message+'">');
            console.log("upload successful!");
            console.log(data);
        },
        error: function(error){ console.log("upload error: " + error.name + ": " + error.message); }
    });
});

To no avail. There seems to be no way of setting a context: in simpleUpload or I would have tried that.

What am I doing wrong?