I have had a cake ordered that is three separated tiers (square) with gumpaste roses between the tiers.  I figured I can build the cakes on the separator plates, inserting the pillars before transport but then assembling the tiers and flowers onsite.  Then the bride tells me that she wants to have the cake moved onto the patio after I have set it up inside.  (our weather could create a hot melty mess if the cake is set up outside prior to guest arrival) The co-ordinator at her venue has assured her that it wont be a problem to move it.  I have never built a cake like this before (I have built somewhere in the neighborhood of 50 to 75ish stacked cakes) and would have thought you should not move a cake like this once it is assembled. I plan to use the wilton separator plate set since those are the ones I can easily and affordable get my mits on. (I am in Canada). Not to mention it seems tough to find these separator systems in the square shape.  any insights, suggestions, experiences with this.  I have to call the venue to arrange delivery of the cake soon and want to make sure I sound like I know what the heck I am doing. lol.

AYou'll. Need to insert the wires of the roses into a styro form so they don't talk off when the cake is moved.

maybe you could decorate on a moving table? that's what we did at work with this one, we just decorated it on the table that it was going to stay on and pushed it into the ballroom. and we just stuck the roses into the butter cream.

AI don't think styro will work because she wants to see the pillars and have space between the top of the roses and the cake above.

I had thought about the moving table(cart) did you have to wheel it over any big transitions in the floor? They want to bring it out on the terrace so there is likely a fairly large metal transition piece to drive over.

That is a very large cake! And super bright! How fun

Is the separator set the one that has 2 plates in between each tier? If so, I wouldn't let that happen.

Otherwise use single wilton "hidden" pillars and ONE plate and have the pillars go all the way through the cake below. And I would ask if they can put it in the cooler instead of just inside if the heat is that much of a problem. If the cake is more solid by being cold, they may have much better luck moving it than if it has already been at room temp for a while. 

AI agree with letting it cool. I always let the frosting harden before I move or stack a cake. We had a large metal bump to cross over and we had two strong guys pick up the table over the bump. I'm pretty sure I was having a heart attack the whole 3 seconds it too to move it. But it turned out fine.