We have some ice producers locally and they carry dry ice blocks... You can buy it by the pound, or they have 10 lb bricks of it...
When I go to Mopar Nationals, I get a brick of dry ice for each cooler and then wrap it in aluminum foil and put it in the bottom of the coolers with pop and regular ice... It refreezes the regular ice after it melts from top and works its way down... Then keep adding fresh ice from the ice machines at the hotel all weekend... It will keep your drinks cold all weekend from Thursday to Sunday... However the drinks at the bottom of the cooler will have ice frozen around them for the first day or two, but will be ready to drink by Sat and Sun...
There should be some ice manufacturers/distributors near Indy I would think...