So... I tried to do a racecar, covered in fondant, a few days ahead of time so I could go out of town for the weekend. I got a call from my bosses freaking out cause apparently everything had bled and melted as far as the detail I had on it. The black windows bled dye into the lime green, the red taillights had completely melted and slid down the back, and the decals I had made wouldn't stick to the over-moist fondant side.
I told them it'd be great to get a dehumidifier for the cooler, but lacking that, what can I do to do these cakes in a timely fashion? How long can I leave a buttercream and fondant cake out of a cooler before they start losing structural integrity and falling apart anyways? Could I wrap my cakes in plastic wrap to keep the moisture from getting to them as I work on them?
I have a 3D sculpted cat and dog coming up, and I dont want to screw them up. So far, I've been able to do most of my work in buttercream, but I do need to master fondant and sugar veil in order to consider myself a worthwhile decorator...
Any help would be appreciated... I'm kinda stuck in a position where theres no one to show me what to do, and it stinks.
~Danika, Cake'N'Bake Decorator

What kind of fondant did you use? I use Satin Ice and I refrigerate all of my cakes. I have never had issues with bleeding, melting, drooping, etc. If a customer wants/needs the cake ahead of time I just tell them to keep it refrigerated until a few hours before the event. If you use MMF, well, that may make a difference, as I have never worked with it so I don't know how it holds up in the fridge.

Short of that, most of the decorators around here (CC) do leave their cakes out at room temp throughout the week while working on them, as long as the fillings/frosting are not of the type that require refrigeration.

The 'cooler' you mention is the problem.
Leave the cake(s) at room temp.- best unless it is very hot & humid in the room. An air conditioned room is ideal for storage of 2 or 3 days.
Do not wrap in plastic - no need to. If possible put the cake(s) in a box, then you can place that into a plastic bag.