Goodness! If you're worried about the fuel cost on your MH, you need to pick another pursuit. I can drive my motorcycle for far less than my MH, but we're are talking Class A's not other vehicles. While fuel cost is factor in ownership it is far from the biggest reason to pick a MH. There are a few of the entry level MH that are designed specificly to capture the indescriminite buyer by being powered with diesel, as if fuel type were important.
Comparing any gas powered MH to a medium or heavy duty powered Coach is completely missing the point, which is lifestyle.