If that 3980 is what the trailer weighs now, you need to figure on adding another 800-1000 lbs not including water. Propane, pots/pans, clothes, food, etc all adds up. If you pack light you could be at +500 lbs bringing the total weight to around 4500 lbs, very close to your tow ratings. Don't forget that about 13% of that weight, or around 600 lbs, is going to be on the hitch, so you need to account for that when you pack the Liberty also to be sure you are the GVWR of the vehicle.
Best thing to do is bring it home, pack it up, and head to the scales and see what everything really weighs, then you can see how close you are to ratings. Just a guess on my part but I think you will be shopping for a bigger vehicle to tow with soon.