Built in or Portable Gen for a pull behind Toy Hauler

If your gen seems too noisy, you haven't turned your music up loud enough yet.

Well if you have the Onan 5500 you are good. They purr like a kitten. If you had the more common 4K "MicroQuiet" you would be singing a different tune. They are rattle buckets.

The convenience is nice but I will NEVER buy another trailer with an Onan 4K built in.

OP since you don't have a fuel station to tap into I think your best bet would be to go portable. Dual Honda EU2000 models in parallel will power your AC just fine. My brother ran this setup on his old trailer and its quiet. Just have to deal with lugging them around and securing them so as to not get stolen. He sold them when he bought his new trailer with Onan 4K built in and is kind of regretting it.

We have the built-in Onan in our Fuzion toyhauler. I don't know where you heard that they vibrate the toyhauler, but you heard wrong. You can't tell ours is running unless you listen for the exhaust noise.

I can't compare portable to built-in, but a portable will certainly be much cheaper. I believe that a Onan 5500, which is what we have, will run up around $4000 if you just go out and buy one. I think the portables are around $800 or so, maybe more for the Honda's and Yamaha's. Which are the preferred brands due to reliability and noise concerns.

The choice between propane and gas would depend on how much you plan on using it. My understanding is that a propane will go through a lot of fuel if used constantly, more than a gasoline powered one would. OTOH if you don't use it much propane is much less hassle when only used occasionally.