I wouldn't bother trying to match with Jeep springs. It's not as if you can swap them off the car & put them on your trailer if they were to break.
Good quality eye to eye springs (Not slipper) possibly like these
http://www.caravansplus.com.au/catal...317610f8642eee matched to the weight you intend to carry would give a good ride. For heavily corrugated roads you may consider shocks as well.