This job is a little to big for me. It sucks.

I've set up and taken down cubes and I've never seen any you could just kick down. The last ones I dealt with were more wood than anything and very heavy and took time to tear down. Unless you're familiar with how to tear these down quickly and haul them off, I would pass. I'm like you. I have a full time job and scrap on the side. I know one day I'll get a call like you and won't have the time because of my job or it will require manpower and equipment I don't have. Sometimes you just have to know when to walk away.