This is a tricky spot, to say the least. Do NOT attempt to get there alone, and a ladder is definitely a good idea!
Opposite the ST factory, walk further away from the terminal till you find a crash gate where the runway is visible. Either prop up your ladder on the side of the gate (not on the gate, as if there's an emergency you might find yourself in trouble, or else see if you can climb on the concrete slabs on the left hand side of the gate.
This area changes often, so carefuly survey the site before attempting to enter. Some landowners in the area may object, in which case it would be a good idea to pack your bags and leave.
Your best option is to use an airband radio, and only "pop up" at the last minute, take your shots and pack up again!