Just go with the dry ice.
No wet stuff, nothing to drain.
Buy a block, and cut as needed into slabs with a circular saw or sawsall
A folded towel in top of cooler will help prevent freezing food you dont wanna freeze
Oh and keep your fingers off it, if you like them.
The simplest safe option for transporting it would be to find some friend with a pickup truck.
Dry ice (“cardice”) sublimates at -109.3 °F. Anything in immediate proximity of the frozen carbon dioxide, or in an effectively insulated container with it, will also be chilled to this temperature, which is cold enough to freeze and cause damage to meats and vegetables. (Household and commercial refrigerators are typically set somewhere around 0 to 5 °F by comparison.) It is therefore necessary to have both an insulating layer on any foodstuff that cannot tolerate such deep freezing and a moderator, as well as a venting path for excessive cold gas that is produced. Already frozen foods that are tolerance of deep cold, such as ice cream stored in readily vented containers such as a styrofoam cooler with an unfixed lid can tolerate such conditions, but most foods will not.
The amount of CO[SUB]2[/SUB] outgassed by a block of dry ice is not generally a hazard in most circumstances as the heavier molecular weight and initial cold temperature will cause it to fall low and vent out of open structures, but in a well sealed structure it could plausibly pose a hazard. Automobile trunk spaces are not typically sealed from the cabin area, but generally have enough venting that a well-insulated cooler shouldn’t produce enough gaseous CO[SUB]2[/SUB] to pose a problem. An open, unprotected block of dry ice could produce enough gas to pose a hazard but I’d like to think that you’d notice the cooling effect and mist leaking into the cabin, as well as the headache and nausea, before it became a serious problem; unlike carbon monoxide, CO[SUB]2[/SUB] levels have to build up to concentrations of ppCO[SUB]2[/SUB]>0.7 psi before they pose a serious medical problem. Be advised, however, that liquid nitrogen in particular is a significant hazard as the body will intake gaseous nitrogen (which is already 78% of the atmosphere) and treat it as a breathing gas without respiratory distress, and at high concentrations where it displaces a signficant amount of the oxygen content it can cause anoxia and hypoxia without physiological distress.
The number of vendors who stock and provide dry ice for non-commercial use has been reducing because of the cost and difficulty of keeping dry ice; it is much colder than most commerical refirgeration systems can sustain, and so continually sublimates away. Using a combination of dry ice and water ice in direct contact only frozen to ~0 °F is not really thermodynamically efficient. While the dry ice will chill the water ice below its freezing temperature, water ice will cause it to start sublimating continuously as well as energy lost in internal phase transitions; in essence, the water ice acts as a thermal mass to keep the internal temperature from getting too low, but causes the dry ice to heat up faster than it would otherwise. If the intent is to moderate the temperature it woudl be more efficient, thermodynamically, to place the dry ice on the bottom, an insulating and thermal mass layer in between, and then food above, but again the ambient temperature is going to approach the sublimation temperature of the ice.
For the most part, it is not really necessary to use dry ice to keep food in coolers at a chilled temperature. Most of the thermal losses are not conduction through the body of the cooler but are convection due to leakage through very poor sealing surfaces, which you can tell because the outside of the cooler is not cold or dripping with condensation. The high thermal gradient and production of cold gas under pressure actually accelerates this loss. A good quality cooler (e.g. a Yeti or Pelican cooler with a gasket seal and polycarbonate construction) will reduce most of that leakage and increase the lifespan of ice, particularly block ice, by a significant factor. You should also not pour off the meltwater from ice as it will remain at freezing temperature while in contact with the ice until the entire block is melted and continue to act as a thermal mass. Pouring off meltwater simply reduces the amount of cold thermal mass to absorb heat. Foodstuffs should be suspended above the meltwater, both to prevent them from freezing and to make sure that they do not introduce bacteria to the water, while beverage cans and bottles should be suspended in the meltwater to get the advantage of conduction, as should any foodstuffs which require freezing or near-freeing tempatures which should be sealed in impermeable packaging.
It is unnecessary and potentially hazardous our to put dry ice into an impermeable container (although Ziploc bags and the like are hardly impermeable) as it produces no meltwater. Wrapping it in paper or insulating materials will to moderate heat flow via conduction but the sublimating gas will be at surface temperature of the block and will dominate the ambient tempature of a cooler.
Stranger