aluminum wire was popular during the period your trailer was built, other members have reported it in trailers from the same era.
just remember to make sure connections are clean and tight, adding an inhibitor to connections is an absoulute must! it can be had at most home centers and good hardware stores. no-ox, penatrox are a few brand names.
keep an eye out for discolored connections, a wire brush will help cleaning them up.
power utilities install millions of feet of aluminum wire a year with good service. aluminum wire is NOT a product of satan, just seems that way when a outlet quits working!
you call them ferrets, i call them weasels.