1992 Coachmen Catalina 19.5 Wiring?

I'm doing some bathroom renovation, namely a new shower and found these wires under the tub, black and red were plugged in to each other. I was also wondering what the switches by the door were for and the one next to the stove.

I see that no one is rushing forward with the answers to your questions.  You would be very fortunate indeed if there was someone monitoring this particular forum who happened to be expert enough about your 1992 Coachmen to know the answers.  I wouldn't hold my breath waiting for him to arrive.  In the meantime, I'll offer a few opinions that may or may not be worth what you are paying for them.

First, in my MH there are two different color combinations for the wiring. For the chassis wiring installed by Ford, Chevy, etc., red is +12v and black is ground.  For the part installed by the MH manufacturer, black is +12v and white is ground.  Thus, black can be either hot or ground depending on where it is.  It would not surprise me to find a +12v red chassis wire connected to a black wire feeding +12v to the cabin.  A multimeter and a long jumper cable to a known ground might help answer your question about the red/black wires.

I assume your mystery switches don't appear to activate anything.  If I were trying to figure what switches were supposed to do I'd ask myself two questions.  First, why was the switch placed here?  For example, switches near the entrance are likely to turn on the porch light and interior lights as you are entering a dark MH at night.  The second question is, what should be working that isn't.  If the switch doesn't appear to do anything, it may be that it is supposed to power something that isn't working.  Keep in mind that you have to think beyond lights to systems like water pumps, water heaters, etc. .... Good luck.

Not sure if yours is the same, but I have an 89 Catalina 240 and the two switches near the shower (in mine they are closer to the vanity sink) control the light above the vanity and the water pump.  In my case, the water pump switch is controled here and on the panel above the stove.  I also have a switch by stove on the wall closer to the sink that turns on the water heater.  It has an illuminated switch when it's turned on.  Good luck! 

JR

Also remember that you have some 120vac wiring too. For that, the black will be 120v + and the white is the neutral (those are industry standards and mandated by the NEC for most installations).

12v wiring has no universal color standards, so you can't rely much on color until you figure out what your RV manufacturer's typical practice was wen your RV was built.