that's all i mostly ever use
i did one unexpected outdoor reception with this scenario and it went perfect--that was in thousand oaks california
i had the cake sealed in corrugated cardboard boxes with ice packs inside and set it up at the last moment possible and it was fine--i usually setup two hours before reception/ceremony--but i only arrived that early--family wedding--and set it out last minute--perfect
here in memphis i deliver the same way--no worries--and once it's inside out of the sun and in air conditioning--you're fine
i deliver that way--all boxed up tight--even a short delivery distance so i don't have an anxiety attack if i get stuck in traffic get a flat stuff like that
i tested this and even in full Memphis sun it holds brilliantly--sealed box--ice packs
ice packs are wrapped in a paper towel to absorb condensation then placed in zip lock bags and firmly secured to inside of box--maybe even underneath the cake
i think delivery packaging is as important as the cake--but i'm a veteran overthinker
not to mention the time i deliverd a pink & blue flowered cake to arrive with pink & blue on one side and white on the other where the sun bleached out the color in the 30 minute car ride
i've pretty much done everything wrong at least once 