You can sneak into the S-300PS at below 25m AGL, and for an effective shot, around 20 km. Same thing with the Buk, and quite possibly the HAWK systems, haven't mucked with the Patriot. The reason you have to get close is that the launch angle is more flatter so it won't get shot down by the SAM's missiles due to the typical pop up maneuver that missiles make for the terminal phase, when shot at long distance, and that the SAM's missiles can of course knock it out of the sky. It's for right now an angles game that hopefully doesn't have to be played when BS comes around.
Problem is that it requires a little bit of nerves of steel with the S-300PS and alot of praying/jinking with the Buk. More than likely since it seems that all have the same behaviour in some respects, the same works on most of them, but have fun in the Su-25T, as I tried it with the -33 and lost my nerve towards the end, but hey, I got the search radar ;)