If your trailer only uses 5 AMP's a day to power the always on stuff in 60 days its used 300 AMP's. You are not using a lot of power if the fridge is off as the trailer is probably only powering the CO and propane detector but there is also your converter fan that might be coming on if the trailer is getting hot enough during the day. Your first improvement after you get this figured out might be installing a battery disconnect switch if you don't have one or a little solar so you don't need one.