NJDetailer, I think you will find that even though your generator is sitting just inside the doors, your trailer will fill up with fumes. I bought a Generac 5500 watts generator from Tractor Supply. I was going to do the same thing with my setup and tried it out last Monday. I let the generator run for 30 minutes while I was breaking-in my air compressor. The fumes inside the trailer turned out to be really bad. 
I walked into the back of the trailer and was only in there for a minute or less. I started feeling lightheaded and my shirt reeked of exhaust fumes. If there's any wind it can make the problem worse. Another problem I noticed with the generator inside the trailer was that it created a lot of low frequency vibration through the trailer and turned the trailer into a giant subwoofer. This happened even though my generator is mounted with pneumatic tires and big rubber cushions under the front. I also found my generator to be very noisy, even though it's suppose to have a quite running muffler. And lastly, the generator generates a lot of heat, which is good in the Winter, but will be bad in the Summer.
I haven't decided how to handle these problems yet, but I'm thinking just because of the heat issue, I'll use it placed outside of the trailer.
I walked into the back of the trailer and was only in there for a minute or less. I started feeling lightheaded and my shirt reeked of exhaust fumes. If there's any wind it can make the problem worse. Another problem I noticed with the generator inside the trailer was that it created a lot of low frequency vibration through the trailer and turned the trailer into a giant subwoofer. This happened even though my generator is mounted with pneumatic tires and big rubber cushions under the front. I also found my generator to be very noisy, even though it's suppose to have a quite running muffler. And lastly, the generator generates a lot of heat, which is good in the Winter, but will be bad in the Summer.I haven't decided how to handle these problems yet, but I'm thinking just because of the heat issue, I'll use it placed outside of the trailer.