Any tips on collecting AP when there are no enemy portals nearby.

There seems to be only two active players near me (N. Lake Tahoe) and we are both Enlightened. There have been a few Resistance players who were active once, but then no activity from them has been seen since day 1. We are rural, with long drives between concentrations of portals. Between the two of us we have control of all portals within a 45 minute drive. I'm now stuck at level three, so I cannot connect the distance between our far flug portals. Any ideas about alternate methods to acquire AP?