I would say the 41qt tub would be big enough. If you're using it with a humidity-friendly substrate (I use cypress) and with lid on the humidity shouldn't be that much of an issue. I let my female maternally incubate last year but she was being kept in a 40g breeder tank and I gave her a lay box lined with dampened sphagnum moss. I also kept a thermometer and hygrometer in there with her to keep tabs on the temps and humidity but the best gauge for adequate humidity is the the clutch of eggs itself. Too much and they look distended and patches of the egg shell may become discolored, too little humidity and they shrivel and harden. Hope it helps and good luck.