When you use the method of 16 campfires, then I suggest that you build a four by four foundation area, with the middle missing, have the campfires placed four by four, light them, then fill in the gap with thatch ceilings. This makes it easier with wyverns because they don't fall into the gap between the ceilings. I have tried this with dinonycus and they have fell between the ceilings. BUT wyverns don't. You want to do relatively the same method as with just campfires, where you have the eggs in the middle, but this made it easier, and Mt wyverns didn't die from fire damage.