I agree.  I would pay an hourly wage, and then they can benefit if they work there tail off.  In salary one will always feel shortchanged when they work 120/hrs in a week for a couple weeks, and then get the same paycheck.  Say $20-35 hr based on experience, or 50-1x0 k range in salary.

I'm not sure what your slower times of the year are, but do you allow your employees to have some extra time off?  Make sure you state that, maybe during a certain month of the year it can be part time, or allow a week or two of paid vacation in the slow times.  You need to state the benefits better, not just the workload and type.

Good luck.