A 2-quart Crockpot can provide sufficient heat for that size kiln, but the water needs to be refilled too often. It also struggles to reach 165°F for flue-curing. I use a 7-quart Crockpot with the lid off all the time. Make sure that your door seal gasket is sufficient.
I have no vents at all. I have a bathroom ventilation fan (designed for high moisture environment) inside, to circulate internal air. No outside air source. If the kilning temp is over 122°F, then no vegetative growth of mold can occur—but only if a circulation fan maintains a relatively uniform temperature within the kiln. I usually run my kiln with a setpoint of 128°F, and a hysteresis of 5°F. So it fluctuates between 128°F and 123°F, running for 2 months per batch. No mold. During the summer (higher ambient temps) I need to refill the Crockpot every 4 or 5 days. During the winter (cooler ambient temps), the power is running more of the time, so I need to refill the Crockpot every 3 days. My kiln is located within an enclosed back porch, with the porch door open to the kitchen throughout the year.
When I flue-cure, I crack the door slightly during the yellowing and leaf wilt stages, then latch it shut for the rest of the run.
Bob