I have never transported a cake anywhere near this long but this might help. These are some important questions: How long are you planning to take to drive this? Do you have A/C in your car and will it be really humid? Does it have a perishable filling? If it is tiered you probably do not want to transport with it fully stacked.
Some people do like putting the cake in the freezer before applying fondant so they get nice edges and the condensation helps it stick but I usually don't unless the kitchen is really hot and/or the BC is almost melting. One thing I have heard of is wrapping the cake in plastic and putting it in a box and then putting dry ice in the cooler with it. Oh and btw some people on here do not like the word "moist" see "Things not to ask/say to a baker" I think it is.