I am wanting to start a small mobile shave ice business on the mainland. I plan to sell shave ice at festivals and other events across my state using a Fujimarca MC-711 manual machine. I'm wondering what would be the most efficient but least expensive way to safely transport my ice without relying on electricity from outside sources. I will only have my car to transport my materials, and therefore would need something small enough to fit in my trunk or my back seat. Any advice, suggestions or insight from the pros is greatly appreciated

I use two sorces, 1st I use an old chest freezer that doesnt work, I have removed the compresser to make it much lighter and I use two large IGLOO Brand Coolers, Both have exelant insulation factors, The Trick is open as little as Possible, when I take a block of Ice out if I dont finish it I have a small cooler it goes into not to have to open my larger ones.

Thanks for the advice El_Piraguero. I'm not sure if I can find a chest freezer small enough to fit in my car but I am definitely going to look into it
I actually saw a pretty large cooler today that apparently can keep ice cold for 5 days in 90 degree heat. I'm very tempted to get that and test it out since it would be so much less expensive...