We have pretty much the same policy on our 2007 3400RL including the full replacement and disappearing deductible (starts at 500) and fulltimers insurance but replacement cost of 62k. We pay $349 every 6 months. National Interstate. It was 398 for 6 months but we just got a letter saying they now check credit ratings and dropped our premium to 349. A very nice surprise.
We also (like adelmoll) have South Dakota, a low insurance rate state, as our legal residence so that is part of the lower rate.