Diesel Motor Home Insurance

I am looking into replacing my 2010 Bounder with a 2014 Tiffin Phaeton. My current insurance is with AAA. My agent told me AAA will not insure the Phaeton because of its value. In 2014, the Phaeton sold for $230,000 with a MSRP of $320,000. The agent said he would have to go with Progressive with a premium of $3170/yr. My Bounder, I am paying around $1000/yr. I can't believe the premium goes up three times when the value only goes up twice. Can anyone suggest an insurance company for diesel motor homes.