I built a roof lifter with pulleys, but the 28# solar panel on top was still really too much - it really takes two people to use a roof lifter with the heavier weight. When the roof is almost up, you have to push on the end panel to pop it into place, for whch a thrid hand is very useful. I thought about adding a locking mechanism, but in the the end we gave up on the roof lifter and bought the gas struts from FWC. I'm sure they will work on an ATC. $250 for the brackets and struts and 30 minutes to install.
The struts work. We pop them off when we set up so they don't get in the way (30 seconds). We have an Eagle - in the larger Hawks and such, you may not need to pop them off. (Sorry, I don't know the ATC equivalents.)