Maybe if they were landing in a risky country (the presidents have visited warzones like Iraq), but even then, they would ensure the airfield and a 10km radius around it would be clear and secure. If they cannot ensure that, how would landing in an unconventional spot improve security? Every part of an AF1 flight is tightly orchestrated on the one hand, and on the other, they would keep the exact flight route and timing a need-to-know secret.