RV Repair: Hook up external water heater, hot water heater, 5th wheel

Question
I am a live-in RVer, parked in a MHP.  I would like to hookup an external 20 gal hot water heater that I have.  I had it hooked up to an older 5th wheel that I lived in, but we had taken out the old RV WH, so it was trial and error, but eventually figured it out.  I don't want to take this one out, because there's nothing wrong with it, except it's only 6 gals.  It's a 2002 Keystone Bobcat 294 EBS, travel trailer.  How can I hook it up, without taking out the orig one or tearing something up.  When I look in from under the sink, the lines coming out of the WH, are very close to the panel that hides it.  I thought I saw 2 hoses hanging down, kinda behind the back tire, on the pass. side of the trailer.  HELP.....I have long hair and these military showers are getting old, and cold!!!
Thank you in advance for you help....Sincerely

Answer
You will need to splice into the lines, it is best near the other WH.  If you want this new WH mounted somewhere different than near the old one, you will need to run lines to the old one.  This is best so the two systems work together.  If you plan to not use the 6gal WH, then put valves in to isolate it.  This way it is not permanently disabled.  Then you need to run propane to the new WH.  Make sure where you mount this new one, it can be ventilated.  Then hook up the electric for temp and starting heater system.  This I would also splice in to the old electric wires.  This way they both come on together.  You wont need to change the switches and wiring.