[JRTJH]

You have at least 4 "phantom drains" on the battery. The Carbon Monoxide (CO) monitor, the Propane (LPG) monitor, the radio memory/backlight system and the TV OTA booster amplifier.

On some trailers there are other drains that you can control (if you remember to turn them on/off: The thermostat, if left in FURN or AIR will continue to draw a small bit of power, even if the trailer is unplugged from shore power (A/C inoperable) the thermostat system is still functional and drawing power, so turn the thermostat OFF to prevent that drain.

As you indicated, the most positive way to eliminate ALL the phantom drains is to either disconnect the batteries or install a "battery cutoff switch (on either the POS or NEG battery cable. Which to use is a debate that we've never resolved with well over 30 years of discussion, so asking "which one" will not get you an answer that all will agree with the poster.