I think I'd find a different electrician.
Seriously, call a couple of local campgrounds and get their recommendations for an electrician. More than one person has had equipment damaged because an electrician wired the outlet incorrectly. When the job is done, have the electrician show you that you have 120V on each of the two legs.
BTW, Newell has a 240V element in the Aqua-Hot that they use. I suspect that we'll start seeing more coaches with higher electrical demands in the future.
Mercury Mountaineer towing mpg 181(both sold)
1993 Foretravel U300 40'