Welcome to the forums and congrats on getting your 2019 375FL Montana High Country.
That is a really unique and special floor plan and that back door on the opposite side will get you a lot of attention wherever you travel. (I know, look at my signature block below)....
We've had ours since new and I've done dozens of modifications on it. One of the very first things we had done was to install an awning over the back door and had LED lights installed that was identical to the front awning set-up.
In time, we added the washing machine and dryer. I had to rebuild the closet as the shelves completely broke on our maiden voyage. The kitchen table and chairs were removed and we put a real table in that spot, and use small short foldable bar stool type chairs now.
I added a fold down arm on the end of the counter top to add extra length when drying dishes.
I re-engineered the closet doors so all 4 panels slide, making it possible to easy access the full closet.
Word of advise: Clothing in the closet will jump off the clothes bar. No matter how smooth you think you are driving, the hangers will jump off. I tried all sorts of cures, but finally fabricated a U shaped black with Velcro straps that fit over the cloths bar. This way, there is no space for the hangers to jump off any more.
I also removed all the carpet in the kitchen slide and installed a laminate floor. The dogs keep peeing on that carpet and it was a mess after 4 years.
The original Rayzor television antenna got replaced with a Wingard 360. After 3 Rayzors breaking by getting caught in low hanging tree branches, I said, enough is enough. I replaced with the Wingard, that has no edges to catch any more.
I replaced all the tires once after the first 5 months we had a blow out. I've been running on Hercules tires ever since.
I also had a bent axle replaced this last winter.
And this is only the short list of things we've done, or had done, or had to have done. Now, it's a really good camper. It does take careful attention to detail upkeep and care. Don't let anything slide. If it goes wonkey, get it fixed immediately.
We have the Samsung refrigerator. We've not had a single issue with it. Learning to winterize it though was an experience though, as is winterizing the washing machine now too.
Your water pump is directly behind the convenience center. To access it, you need to remove the back wall of the bottom storage pass through. There are 2 panels, each one is attached with 4 screws. You have to fishing around in the carpet fibers to find them.
If you accidently flip the winterizing valve after filling the water tank, your water pump will continue to run and never shut off. It's REAL easy to flip that one when you think you flipped the "fill" valve.
Also, if you fail to flip the "fill" valve, the water pump will periodically kick off for a couple seconds every now and then. It will make you think you have a leak. Not so.
Water heater works well on gas or electric, and both at the same time. You should have a 12 gallon water heater tank.
Good luck with your new camper. Any questions, please feel to ask. I've been through the gauntlet with mine. After all the work I've done it, it's NOW a darn good camper!
Happy camping! Enjoy!
Who you are right now is a sum total off all you use to be.
2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually