Do you have a thermostat? a UTH? Whats your humidity?
Holes in the tub are the least of your worries. One or two holes are fine if you need more humidity. If you need to lower humidity then put more. Snakes need much less air than a mammal would.
Sounds like you should do your homework and get your temps and humidity in order before you put your snake in a new enclosure.
Once again holes are one of the least important factors.