You could but you'd have a rucksack full of power supply and battery. The guy's design seems pretty sound and all the parts are commercially available, the only criticism being that he should have perhaps used a diode or two in series with the batteries to keep the volts under 15V for the Duracell inverter rather than a resistance.
Posts made by Hector
RE: Any problem with recharging Onewheel using my car battery and an inverter?
RE: Charging from car inverter or portable battery
the UPS made for computers use a smallish sealed gel cel battery, usually 10 to 18 amp-hour size. those could probably run the projector for about an hour. check this