There are two good sniping spots at the Temple.
1. Play as the Empire and choose a sniper. Get on a speeder bike and head over to the Temple Command Post. You can ride the speeder bike up the side of the temple and snipe the rebels as they leave the CP.
2. Play as either side and select a sniper. Head to where you can enter the long viaduct that goes across the battlefield. Get on the viaduct and find a good sniping spot. You can shoot enemy infantry fairly easily from up there.