g/c is using a 30 amp extension cord as i read the post....
yes one can run an extension cord from the genset to the rear trailer plug.
what matters is selecting an extension cord properly sized to minimize lost voltage....
10 gauge is my choice for this application.
there are tables that list extension cord length and wire size required for proper voltage.
i also use a plug sized gadget inside the trailer which constantly monitors and reports voltage and hertz (cycles).
so as i noted initially the gen prep option is NOT that big a deal.
an extension cord works just fine.
i would not go to the expense to retro fit a gen plug unless already doing electrical upgrades (new converters/inverters, wiring and so on)
on a related note i almost never leave the genset in the tv. while in use....
it would be too easy for me to hop in the truck and drive away while still connected!