thanks for the reply Ramjet.
I would prefer not to set up panels everytime i need a charge and would like the safety of having them mounted on the roof when i am away climbing, etc. for the day. Seems like there is always a trade-off in permanent vs. mobile. Seems if they are on the roof, atleast a charge is always occurring.
Cleaning the dust/snow off is not a problem, but certainly another thing to do. I hope having a panel on the roof would not result in damage. I am mostly concerned with the panel vibrating/flexing on the rooftop over washboard desert road, not being familiar with the integrity of any panel in this use.
My power usage is minimal. Running a newer 50L ARB fridge, camper lights(minimalist), water pump, portable dvd player, and a laptop charger would be the average uses. Just not interested in a dead battery