My fifth is only wired for 30A and has a fireplace. However it is wired thru a toggle switch where I send the power to either the Fireplace OR Elec water heater. When it gets cold here (below 50) we stay at home so it hasn't been used.
2008 Jayco Eagle SuperLite 29.5
2014 F250 6.7 PSD 4X4, CC LB