Need more information. What type of thermostat and what type of electric heater? Are you blowing an actual fuse in the thermostat, at the 12 v fuse/circuit breaker panel, or a 120 v circuit breaker in the power panel? Since it's a 2013 model, have you contacted Winnebago or a service dept. for hints? It would be very rare for a 12 v thermostat that just sends a signal to turn on or off a 120 v heater to blow a fuse unless wiring is incorrect or shorting out due to compromised insulation on the 12 v control wires.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI