I build ceilings on layer up put a bunch of ramps on them and fill under the ceilings with as many ACs as I can fit. Makes a nice place to hatch tons of eggs at once.
I use 20 to be sure but I think 15-18 and you’re good, it’s not the same as wyverns which is 9 unless they’ve changed it... haven’t hatched a wyvern in a while