We did the following test when we added a dorm fridge
to see how long we could run off the battery. It should provide you with a good first order answer.
Plug your rig in and fully charge your battery (about 12.65 volts). You need to run the converter to charge it. To find out if it's fully charged you need to shutoff the converter (un-plug the rig) and wait a few minutes to let the battery normalize and then measure it.)
To run the test unplug the trailer and turn the number of LEDs you would typically use and what ever else you use. To test for the water pump load, run the water for the number of minutes you might in a day. (Actually the number of minutes a pump runs in a day is not many) and check the battery voltage every now and than.
When the battery voltage drops to 11.6 it is considered discharged. (I am not sure that it's 11.6 but it's certainly at a state that you would no longer want to discharge it.)
Doing this for a couple of days will tell you how long you have. You should be able to test for two days in one by leaving the lights
on for 24 hours.