Relocate water heater switch

I would like to relocate the water heater switch to the inside of my 2018 Rpod 180.  I am however having difficulty figuring out which wires I need to extend.  I looked at the wiring on the water heater and got confused, anyone out there have experience doing this? Any help would be appreciated.
Thanks, Tony

Ok, thanks!!

Alan, yes, it's really easy to put a switch in the wire from the breaker to the water heater.  I did it in about 15 minutes, once I got the switch box, screws, switch, etc. (all repurposed stuff) together.  It's super easy.  We've got a 172 and the water heater is under the port side dinette seat.  I mounted the switch there and labeled it with a warning not to turn it on unless there is verified water in the water heater.  Total cost for materials:  <$2.

if you don't use the same model switch as Suburban uses on the water heater itself, note that the water heater element is rated at 120Vac, 12A, so you need to get a switch with that rating.  You should not try to use a 12Vdc rated switch for that application. 

Thanks for all the tips!, I popped out the original switch and extended the wires about 3 feet, carved a square hole and mounted the switch beside the GFCI outlet below the bed, so far so good. So much more convenient.