First of all, welcome to our crazy-awesome fanmail community!!
Second, I haven't tried it personally, but I have heard of others that did what you want to do, and ending with successes. However, you might have to pay a lot of money to send it, so make sure that the address you're planning on using is successful as well. And, I think you said that you have a SASE or something of that sort? As long as you include that you have one in the letter of request, it should be fine.

I'm new to this forum and was curious if anyone had success sending movie posters rolled in a tube that was SAS and then placed in another tube for sending to the person you wished to autograph it? Am I breaking fanmail.biz rule by doing this?