Get one installed in the trailer. Quieter, less hassle, more power.
The other thing to keep in mind is what your using it for. If you're gonna run a roof A/C unit, that's gonna draw 2500-3000 watts by itself, and an additional 500 watts to start up. You gettin a microwave too? That's gonna use a couple thousand watts to power up too.
Our 18'er doesn't have the internal space so we bought the 5000 watt Costco special for $500. Used it once, and returned it - way, way loud, like a uncorked 426! It even said "Great for RV use!" Yeah, if there's no one within a 3 mile radius! Our problem is, we need a QUIET portable that puts out about 4000-4500 watts. Haven't found the ideal price vs. noise balance yet.