i can't give you too much useful info really since i don't actually use sagat, i just do combos and stuff for fun
i don;t know the best application for tiger knee but apparantly it beats out everything except for ultras, so i guess its used for priority like kens dragon punches. perhaps stick to lk/mk tiger knee for its reduced range?
ive watched your vids and my gameplan would be similar to yours, just keep them the hell away because they have a lot of work to do to get close. once your ultra is up, replace your normal hk you use as anti with wither forward hk or tiger uppercut FADC combos to make use of the ultra.
its seem like most of sagats tools are designed to space anyway, i mean both his throws and stuff like tiger knee/ ex tiger shots knocks them a full screen away lol!
perhaps this thread will be more useful to you, its a breakdown of all his moves and bread and butter stuff
http://forums.shoryuken.com/showthread.php?t=160652
i find watching tourney/match vids is always helpful for ideas and setups. i bet you'll find some good stuff by watching what other sagats do forced to fight up close and maybe find some useful stuff about tiger knee