Ditto to Boots, what sort of fridges are they ?? battery size is needed before a reliable answer can be provided.....
but a general answer would be, 3 way fridge NO, they don't do 12v and will eat a battery in hours if not under constant charge , a compressor fridge in van probably NO as they need at least a 120ah battery for themselves with daily charging, if running a beer fridge it would need a similar battery capacity to operate ... so ball park figure if the aux battery is 200plus ah lithium with a decent sized solar panel hanging off it and your van and beer fridge are compressor models then probably yes ........ charging using a vehicle is not a great idea .....
Any leads as shown would need to be a minimum of 8 B&S to minimise power loss....