Seems no one has pointed out the obvious -
why you would want to run your water heater on both modes simultaneously. Answer - quicker recovery, so your wife doesn't yell at you halfway through a shower. :W
Assuming your Suburban hasn't been installed with an switch inside the trailer that can be used to turn the electric mode on / off just add your own as I did with our previous K-Z Spree. I used a paddle switch with a built in light which would indicate when the water heater's electric heating element was on ... much easier than running outside.
