Ours is set up the same way.
I think you might be wrong, but not certain. I have no scientific evidence other than my electric bill. That is not hard proof, as we run the heat pump less in the winter than we do the air conditioner in the summer. After I try to make allowance for the shorter winter running time, the heat pump "appears" to be less expensive. And the power draw from the heat pump seems to be less than either the aircondx or the propane blower.
The propane likely uses so much electricity because we run the separately switched basement blower when it gets cold enough to use the propane system. I leave the basement switch on all the time. When we had the coach built we specified cold weather protection, so we have the basement blower and also the heating pads for the tanks.
So far the most economical approach "seems" to be (no scientific evidence), run the heat pumps till temps drop below 40, then switch to furnace, if the system has not already done that for us.