Even if you find the original manual, you're likely to find it is too generic to be of much use.
Look on each component (water heater, fridge, water pump, converter etc.) for brand and model # and google that.
Buck: 2004 Wilderness Yukon 8275S, now memories.
Star: Open range LF297RLS. 2 air conditioners!
Togo: 2014 Winnebago View Profile, 2013 Sprinter chassis; 16 mpg
Snow: 2020 F250 diesel
AD5GR