Guys,
Good answers, and lots of good thoughts.
The sticker is there to indicate that you should insure there is less than 25 ohms (though an arbitrary figure, CAT and others, use it because every electrician understands it) between the generator and what you are standing on.
The last thing anyone (and certainly CAT) needs is a difference of potential between a trailer sitting there in the open where anyone can touch it, and the trailer which is mounted on rubber tires.
A fault or inductive build up is one thing, the gen has plenty of safeties to deal with that, but if someone is touching it during that period, we want to make certain they don't get hurt.
They also don't want the electrician, or tech, to get zapped trying to crawl up on the trailer when trying to service.
There's a good half dozen proper ways to hook up a ground to a gen depending on your service type, etc. They're just trying to make sure you know it needs to be grounded at the frame to nearby ground, if you don't, it's on you, cause they put the sticker there.
