Made the deadline!
I ended up frosting the cake and with the very last of the fondant scraps I had I did an outline of the original pattern. Looked pretty okay. She was beaming as she toted it away so I'd say she mind the change in decor.
And for future reference: There's a reason all MF tutes have you use white mallows. Either the color or the flavor that's in the non-white ones DO NOT LIKE MICROWAVES. The ones I tried pretty much refused to melt and actually got kinda scorched -yes, there was water in the bowl.
Again guys, thanks for the replies