You aren't dealing with a lack of oxygen. Your Nighthawk is measuring the amount of carbon monoxide in the air. I'm assuming that your standing pilots could be a source, although it could be the furnace also but I assume you are not using it.
Now if your trailer is nice and tight you will get some buildup. My guess is you have always had some amount but the oven pilot kicked it over the threshold of your monitor.
Personally I don't have a good solution other than to not use the standing pilots and use a spark ignitor to lite the gas burners when you need them. I'm also assuming you can shut off the pilots easily.
Here's the table from Kiddie regarding your detector and the values shown on it.
100 ppm within 2 to 3 hoursSlight headache
400 ppm within 1 to 2 hours Frontal headache within 2.5 to 3.5 hours Widespread headache
800 ppmwithin 45 minutesDizziness, nausea, convulsions
1600 ppm within 20 minutesHeadache, dizziness and nausea within 1-2 hours !!!!Death !
3200 ppm within 5-10 minutesHeadache, dizziness and nausea within 1 hour !!!!Death !
6400 ppm within 1-2 minutesHeadache, dizziness and nausea within 25-30 minutes !!!!Death !
12,800 PPMwithin 1-3 minutes !!!!Death !
EPA standard is 50 ppm or below averaged over an 8 hour period.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700