I'm on a 7 month road trip and right now I have a huge hard side ice chest that's taking up a lot of needed space in my car. There'll also be times when I won't have acess to a frig to refreeze my dry ice. Will a smaller soft sided cooler keep my 2 packs of dry ice cold just as long as my hard side cooler? In other words, what better at keeping things cold; hardside or softside coolers?