Originally Posted by tawoo
I think I will do just that. In my camper my hot water tank is in the rear as well as my shower. I think I'll tee off the line that feeds my camper's hot water tank. It should be easy to do as I have access to it under my bottom bunk bed.
Sorry, that won't work the way you plan...
The line to the camper's water heater is low pressure (11"WC, about .4 of a PSI). Your portable water heater has it's own regulator and connects directly to a propane tank (about 150 PSI @ 68F).
While connecting low pressure propane to a high pressure appliance isn't dangerous, the appliance simply won't function.
To run your portable water heater off the RV's bulk tank, you have to T into the (very short) line between the tank and regulator. An example: Camco RV 90-Degree Brass Propane Tee with 12' Hose - Walmart.com
But there are plenty of others. Make sure you use a factory built high pressure hose!