Adding just a single extra Quiq charger can cut your charge time in half. Highly recommended. You can use 2 Delta Q's (750-960 watts each) on one 20 amp outlet (the one with the horizontal and vertical slot on the right hand side). 20 amps * 125 volts = 2500 watts max, but only 2000 watts continuous (80%).
At very low states of charge (under 50%) you should be able to run the onboard and a delta Q from one single 20A outlet if nothing else is on that circuit. Example if you unplug the coke machine or ice machine plugged into the outlet you should be able to run both chargers without tripping the circuit.
What I really recommend is carrying 2 quiq chargers (delta q's) and an extension cord. Park close to a 20A outlet and run both delta Q's off that. And use your 50 foot (14 gauge or lower) extension cord to plug the onboard charger to a different outlet on a different circuit.
If you stop for an hour and a half for lunch and conversation with other bikers on a group ride, you can recharge about half your battery back during this time.