If you're parked for longer term work situations, It might be cheaper to buy a window unit and run that off a separate cord to the pedestal. If you're pretty set on pimping what you have, a good electrician should be able to set you up with 50 amp service and then you can shop for a second AC.
BTW, have you cleaned your existing A/C unit lately. Most folks just expect them to run forever but they work better when maintained. If you haven;t cleaned the condenser coils and filters for awhile, I'd bet a cold one that doing that will lower your inside temps by 5 degrees.
