A generator is great for electricity.  But an engine produces carbon monoxide in the exhaust.  The gas is colorless, orderless and deadly.  Many people have died in cars sleeping with the engine running.  Many people have died in houses with generators running.

I take all precautions against CO getting to me when using the genset.  I place the genset so prevailing winds move exhaust away.  I have a cover to shield the genset from rain while running.  (it's just a roof with no sides)

I wouldn't run it inside at all. Google " horse trailer generator carbon monoxide " and you will find numerous stories of deaths from that exact thing. Here's one; http://www.thehorse.com/ViewArticle.aspx?ID=8145

And here is a CPSC study; http://www.cpsc.gov/library/coed05.pdf

Also, I was at a team roping where a generator was running in a horse compartment and vibrated over against the rubber on the wall and caught on fire. Better safe and sound than the alternative.

Don't think that's a good location when you're sleeping in the GN bunk.  Rising exhaust gases will enter the space.

[Put it under the gooseneck on the ground.

That's about the worse place it should be located.

The best set up I've seen for a portable generator, was utilising the trailer's rear tack area. A plywood tray was made using heavy duty drawer slides, and mounted to the floor under the saddle racks. A portable Yamaha generator was set on the tray. The slides were either 100% or 110% over travel, and when pulled completely rearward, allowed the generator to run entirely in the open. The unit was placed so the exhaust ejected rearward, away from the trailer. When not in use, the generator was pushed forward into the tack area under the saddles, and was secured by the tack door's lock.

Any refueling was also completed outside the trailer, with no chance of inside spills. The installation was a very good use of available space, protecting the generator from the elements and pilferage, whilst ensuring the exhaust direction and maintenance issues were easily addressed.

Ours, in the rear tack floor, is a permanent mount, then encased in a (per Onan specs)custom insulated aluminum cover, ventilated, that is bolted to the floor.  The noise is ridiculously quiet, and the exhaust is piped out the bottom and to the opposite back corner from the entry door to the LQ. 

It does not get bounced around or vibrate, there is a screened louvered air intake in the tackroom door, the engine cooling air (heated by passing over the engine to cool) vents out the bottom, and there is an access port to do the oil change from below.  The fuel is in a custom fabricated 20 gal aluminum tank permanently mounted, with vent cap that vents below the trailer with a tiny line, the tank is located in the rear lower manger compartment... when we fuel up we just open the lower manger door, remove the cap and fuel up at the gas station.  Everything very solid, but accessible. 

If in a grassy area I put a large flat composite rectangular fireproof sheet under there (like goes under a wood burning heater etc) just to try to be extra safe on that sort of thing..