Yeah, ths is not really a goer. Especially for a fridge.
There is one thing I've done which really is the quickest easiest, cheapest reasonably low cost way to install solar panels.
Look for ETFE encapsulated flexible solar panels. These are far more durable and longest lasting of all the flexible solar panels. Do not use PET encased solar panels.
Clean said roof with dishwash and warm water. Finish with methylated spirits.
VHB tape the edges of the solar panels (I've done 100w solar panels like this). You might need to drill or pry out any rivets so you get a good bond in the corners. You'll need to be really accurate putting the panels down. If you plan to do more, leave space for them.
The trickiest part is finding somewhere to route the cables into the cabin/shell/whatever. I'll never put a hole willingly into a roof unless absolutely necessary. I've generally gotten by in the last three installations by reusing an antenna hole. I cut off those MC4 connectors and solder with hot melt glue and heatshrink. Tidier and less fugly.
Profit with solar!