I would like to make a large cake for my 9th grader's graduation (I am their teacher).  There will be about 250 people.  I have a pan that is a tad bigger than half sheet.  My plan is to make a 2 layer cake with each layer approximately 2.25 cakes (I want to fit the size of the board that I have to present it on, as well as to stagger the layers so that they hold together more nicely).  I have some nice cake recipes - I have used them and get consistent results, a chocolate cake made with cocoa and a white chocolate cake made with sour cream.  They are equally moist and "dense".  I did some simple decorating many, many moons ago..(understand the term "President Reagan"?)  but never anything this big. 

My questions:  I am looking for the most most stable frosting/icing I can find.  Is the "decorators cream cheese" likely to be it?  The cake will sit in a room that will probably be 80 degrees or more for several hours.  I can keep my apartment at 70 degrees while frosting, and throughout the night.  The frosting will be white chocolate, probably mixed with shredded coconut, and have simple borders at the top edges and bottom. Decorations on top will be fresh strawberries and chocolate words, drizzled chocolate and strawberry sauce and possibly shaved chocolate or pieces of chocolate.  I may cut strawberries and put them on the sides of the cake, possibly using toothpicks to hold them in place.

If I put a crumb layer on the top of the bottom cakes, can I get away with putting a thin layer of strawberry puree on top of that (the layer between cakes)?  Or can I use thinly sliced strawberries between the layers? It will sit for about 16 hours, 12 hours at 70 degrees and 4 or 5 in a warmer area.   I am trying to tone down the sweetness, if possible, by using strawberry puree but I don't want the bottom layer of the cake to be sopping wet, like a sponge. Would adding a little bit of corn starch to the puree help?  or gelatin?

The decorations don't have to be fancy, but I want it to look "clean", smooth, with nice lines, not unbalanced or uneven.  I was thinking that by using dried coconut that I can get away with the top icing not being so smooth - will that work? Should I mix the coconut in with the frosting or sprinkle it on top?  How do you manage the frosting on a cake this size?  I have look at many youtube videos and they all talk about putting the cake in the freezer for 20-30 minutes to let that prior steps harden, but I don't have that option. 

Finally, is there some way to dip the strawberries in a very light coat of chocolate so that the details of the strawberry are still visible?  Rather than having a blob of chocolate that vaguely resembles the shape of the strawberry?

I will appreciate any advice that you have.   I know that I am jumping in way over my head...but sometimes I find that I learn the best when I do that.

Not much help but I have never frozen or even frogs a cake to harden icing   With the house at 70 there should be no problem w/ icing setting up w/in 20-45 minuets—If Using b’ cream especially if it crusts 

a nice challenge for you — cool

with the specs you listed I would recommend that you avoid cut strawberries because they will likely bleed over that period of time/temp especially if using toothpicks— perhaps if they are sliced with a very sharp knife they won’t leak as much but I keep mine cold in the fridge and the cut ones I never have on the outside of the cake—so I am cautioning you to test your berries in those conditions if you want to go that way but I would avoid fresh cut fruit completely myself  — surely they will leak for you unless cut and placed way way last minute on the day of —

the cream cheese can sicken people if left out that long so that’s definitely out —

for the berry filling — maybe but you need to run a dam of icing around the outside top perimeter of the layer — and you would probably be ok with that but depending on the type of filling it might/might not get soaked up into the cake —

what you could do that would be easy to control and fancy is to squirt a scroll of strawberry coulis  on the non-paper plate under the serving or on top of the slice if using paper plates 

I would say to press the coconut onto the sides of the cake immediately after icing — if you want to add piped details after that — then just squish/move the coconut away from that area with your fingers or a knife —

for example to pipe a bottom border on a cake with coconut covered sides — squish the coconut up into the rest of it — then pipe

this link gives you a shelf stable cream cheese like recipe but if the temp got into the 90's it would get pretty soft --

https://www.cakecentral.com/recipe/61811/white-balsamic-american-buttercream

and this gives more info on building the dam for cakes filled with slippery fillings

https://www.cakecentral.com/tutorial/61807/filling-fortification

what you want to be sure of is to have an inflexible bottom board -- I use foam core board -- for this i would get the half inch thick stuff -- be sure you can lift/carry this puppy when it's finished --

do you know how to deliver cake?

and as a new member you probably cannot "reply" to threads for a while so please feel free to being a new thread to respond and continue the discussion -- best to you!

I agree w/K8 about fresh strawberry especially the cut ones    Not knowing better yrs ago I went through the major problems of them leaking:(   Believe me NO fun!