Hide, run, hide. They won't blow you up if they can't see you (unlike the sniper shooting the cars in Minefield) and as long as you time your runs well and have a recent save you can get it.
Took me about 5 tries before I found a good pathway.
I also took up the bet with that guy who says if you give him 300 he'll give you 600 caps if you make it to the gate and back...then he walked right out into the open and got blown up, so I took my caps back plus the additional 300.