So it does not smell dirt or earthy or even like sewer water. We even bought a special air filter that is suppose to be used for formaldehyde that made little difference. It has always smelled chemically/perfume. I have never smelled the smell, sticking my head into a bulk head or cabinet or smelling right up against the wood.
So this weekend I located both of the black AAV valves, removed both, and simply put doubled up plastic wrap over both the kitchen and bathroom vents. I then used tape to secure/make sure they are air tight. I've also made sure that all p-traps have water and then stopped up all sink/bath drains and added water so that I can visually tell that there is nothing coming through those areas. I did the same for the toilet. I have now left it open to air out for going on 48 hours now and I have to say the small is significantly better today.
We took out everything that wasn't glued/bolted down out of the trailer on Friday and all of that stuff carries that smell. So now we will febreze anything cloth (window valences/blinds) and see if that helps removing any residual smell from anything fabric/soft surface.
This is starting to make sense though as the rear bunk area has never had the smell as badly (furthest away from kitchen, but has the same cabinet/wall/floor building materials. The main area/master are more open to the kitchen which has one of those AAV valves, and at times the bathroom has had the smell, but it often has the door closed.
Thank you for the input and I will report back after we give it a few more days, but so far this is the most progress we have made in months!!