Casey! Davidson market, sounds like fun. It's always been way too far for us to travel but it's a nice market!Again there is no perfect solution. Everything has tolerance and associated costs.When outdoors you have ambient temps and humidity.Every time you open a holding container, electric or not, you will lose temperature and introduce humidity.Being busy will increase this exchange by a magnitude.No solution will obviate this, and most if not all will only solve the cold rebound. Ie how long it takes to turn to a cold temp.Another axiom you come across is the faster you get the rebound the more water crystals manifest. At least for those of us in humidity belts. You see you trap the humidity then the cold creates a dew point. You can keep your product cold but then keeping it dry becomes your next hurdle. There is always something.So.. What we came up with after taking coolers, freezers, and fridges out--you create a series of containers. No high tech thing needed, no dry ice either--humidity is worse than lack of ultimate chill.Standard freezer packs. Large squares work great. For each cooler pick up 3 or 4.For us in June, 85-95' heat, 70+% humidity we would take 3 to 4 coolers. The lot of product for the day is organized by splitting the contents among the coolers in somewhat even amounts--this can be also axed by items of popularity. Bag your items in their categories, this is assuming your products are already boxed or packaged too. If you are selling individual chocolates, we stopped this but when we did we handeled it similarly. Large tubs replicated. The main goal of bagging is to keep moisture out by giving everything more time. In this model you may breach the container but if you keep additional humidity from other items you can sustain one cooler longer before needing to transfer.Ok so you start the morning in one cooler, that's one cooler that has been breached, only one getting contaminated by air and humidity. The day wears on and you migrate remaining products to next cooler, and onwards as sales or slowing of coolering or increased humidity/liquid becomes a nuisance.Time of year, craziness of weather, all dictate the speed and need to handle things in such an order but you do it a while you find the knack for keeping pristine chocolates and butter ganaches safe all day long.On the flip side my love of winter has grown. In December I need no ice, and can lay all produce out. Makes me so freakin happy. I abhor a July afternoon at a 5'oclock market. Luckily we don't have to do many of those anymore.
So! No cords, little clean up, and just freeze your packs again--gtg. I've always wanted something slicker but slicker has a huge cost or a huge weight and both always end up breaking or sucking at some time or another. "Keep it simple stupid" really seems to boomerang me on this one.