Tampon For 9 Hours?

I'm about to start school and am not able to change a tampon every few hours. I really dislike pads and would like to use a tampon.. I would wear both a pad and a tampon, and am not so scared about leaking during the day.. what I'm scared about is TSS. I would put a tampon in around 7am, and take it out as soon as I get home around 3pm. Is this too long? Will I get TSS? How long do you leave tampons in? What happens of you leave it in more than 8 hours? Also, Ive never used a tampon before cause I'm afraid of TSS and that it will hurt when i take it out..