Lot of possible varibles here. Are you going to be hauling bags of lime? If so, I assume you want to place the pallet of bags somewhere for temporary storage, other wise if you are going to immediately use the stuff it would be better to drive the trailer to the job sit and unload as needed to apply. Easier to unload from trailer rather than lift from the ground.
You will have to have a pallet or pallets at the front of the trailer or you will not have enough weight on the tongue. I assume you have thought of that and plan to drag the pallets to the back to unload. That's fine, but can you fasten the rope to the pallets in such a way that you don't tear up the pallet when dragging? What happens when you have one heavy pallet at the back of the trailer? The load will try to lift the tongue and may, depending on the load, pick up the back of the truck. A solution to that is to have jackstands or blocks under the back of the trailer at each side.
Another issue is what happens when you drag the load off and the pallet hits the ground. I think a heavy load will break the pallet.
Going back to having the pallet at the back of the trailer and the trailer supported properly. There are 3ph implements made with forks to handle large round bales of hay. Possibly the forks are the proper spacing to lift a pallet and they are not too expensive. You will have to find out how much the 3ph hitch on your Kubota will pick up and determine if it will raise high enough to lift the pallet.
Hope this helps.
KEH