That UPS is twist lock for a reason - I believe the lowest draw a 110 twist lock will have is 20 amps. IIRC, APC's biggest 5-15P plug UPS used to be a 1000 or 1200.

They are available with 2.5 meters of 3 x 12 AWG, SJT cable and are configured with a NEMA 5-20 plug and terminated with one of three angled IEC 60320 C19 connectors: left, right and straight.