Well, the appliances are over 38 years old... Doubt you are going to find replacement parts for them.. You'll have to have a good understanding of how they work first in order to be able to troubleshoot the issue with them and then fix them.. Fridge might have already lost all of it's ammonia, so it won't work even if you get it fired up??
Might start out by making sure all the tubes/flues are clear of debris and you are getting gas out of the burners. You do know how to start a manual pilot lit device, right? The sparkers might not work anymore, so that would be the first thing to check out.. How do you do that? No idea.. I just knew how to light them when I was 13 years old.. ;) I do remember having to use those long wooden match sticks too.. The sparkers on the trailer didn't work all that well when it was new!
It does all start with having 12v power thru out the rig.. The sparkers probably don't need 12v (I have a coleman stove with them and it does not need any power for them) so assuming you have 12v the rest is just making sure the mechanics still work, which sounds like they don't...
It's a restoration project IMO... Unless everything works already, it's gonna take some time, knowledge and $$ to get them working again..
Good luck!
Mitch