Take out the total side window, frame and all. The doors come off the fridge and it comes through the window on its back.
Don't do what a camper neighbor did! He measured everything for the fridge to go into the cavity, but after purchasing the fridge, he found out that it could not go down his hallway to be inserted into the cavity.
Two other points; your MH may not have an inverted electrical outlet at the fridge site and the inverter may not be large enough.
Gale & Hank- 2012 Berkshire 390BH