Snowflake eels escaping?

Exactly how concerned should I be about a snowflake eel escaping? I'm
starting a 75 gallon fish-only tank and want to include a snowflake
eel. My tank is well covered, but I do have two openings on the back
of my tank to allow for filtration hoses and a hang-on protein skimmer
and a heater and powerheads. The openings are about 2" wide and 10"
long (long and narrow). I know an eel CAN escape through a hole that
size, but WILL he? I've heard stories about people waking up to find
a dried stiff eel on the floor next to the tank. Are stories like
this the exception or the rule?

Thanks...
Gary