OK, you have the 376FL or the 377FL? Right? Your High Country has the loft above the master bedroom, and rear door on the opposite side? Right?
If so.... I have the 375FL, which was the model before yours.
All of these models have the same floor plan with the back door on the opposite side.
(374FL - RV refrigerator, 1 battery)
(375FL - Residential refrigerator - 2 batteries - inverter)
(376FL - built when the 374 and 375 were discontinued - RV refrigerator, 1 battery, loft with stairs behind bathroom)
(377FL - 2nd generation of the 375 - Residential refrigerator, 2 batteries, inverter, loft with stairs behind bathroom)
Your water heater is located behind the stairs going up into the loft. It will accessed through the closet behind those stairs accessed from the bedroom side. The bottom floor of that closet has to be removed, then you can accessit.
I installed a washer and dryer in that cabinet and pulled the floor out to reinforce the floor and supports to better support the washer and dryer. Here's what it looks like:
Before adding the washer/dryer:
Removing the shelving, exposing the water heater, reinforcing the supports for the washer:
After the install: