Yes - see my edited post above.
I am not familar with LARGE portable generators like yours, but I have an uneasy feeling about larger portable generators (above 5kW?) that have a different config on neutral bonding requirements etc. I beleive it is a OSHA requirement for construction safety? You may want to investigate that a bit more. There are lots of discussions on the web, and RV forums about neutral bonding, etc. It might be a red herring on my part, but I do not know......
Sorry I cannot be of more help here.
Brian
Edit: I did a little research, but
you must confirm this information with a qualified electrician in your area.
Here is the OSHA fact sheet on grounding and neutral bonding.
Here are a two interpretation letters from OSHA
Letter one,
Letter two.
In my review - the 4 prong twist lock with two hots has the neutral bonded to the generator frame - from the interpretation on letter one
The intent of 1926.404(f)(3)(iii) becomes very clear when one considers that the term "neutral" is used in its technical sense. A 120/240 volt system has a neutral and therefore must be bonded to the generator frame. A 2-wire 120 volt system has no neutral and therefore bonding is optional. Recall that neither side of a 2-wire derived system is a neutral and when one grounds either side, it becomes a grounded terminal or conductor, but it is not a neutral.
I would be highly uncomfortable with the possibility of loosing the neutral and sending 240V to the trailer. You may be more comfortable. Good luck.
In my thoughts, if you are looking only at powering the RV, considering one AC and maybe a microwave at the same time, a 3000W with no 120/240 4 prong twist lock may be adequate.
Brian