[DutchmenSport]

"Then there is the problem of adding a freshener or sanitizer.
I tried to add it through the vent in the rear with a funnel. The solution or even water would NOT drain into tank Unless under pressure!"

Your Montana does not have a gravity fill port. In order to fill your water tank, you attach a garden hose to the fresh water in-let, flip the valve and fill the tank. If you flip the valve the other way, you can run water directly from the garden hose and nothing goes into the fresh water tank.

There is another valve in your wet bay for winterizing. What you do is, prepare your sanitizing solution in a bucket and then use your winterizing system to run the sanitized water through all your pipes.... exactly like you would do if you winterized with pink-stuff.

In order to get the sanatizing solution into your fresh water tank, you attach your outside shower (that blue coiled hose) from the faucet to the fill port and flip that valve to fill the fresh water tank (same as if you were filling from a garden hose).

You now flip on your water pump. It pick-up the sanitizing solution from the bucket, flows through the water lines, comes out the shower (blue coiled hose) and into the city water fill and into your fresh water tank.

It sounds like a lot, but it really is very, very easy to do. It's exactly the same thing as winterizing with pink-stuff, with the addition of using the outside blue coiled hose to add the sanitizer to the fresh water tank.

Easy peasy.

Another tip, if you ever find yourself with no hot water, say or example the water heater failed for whatever reason; you can always heat water on the propane stove, and then pump it through your winterizing system. I actually did this once so we could take warm showers. I put the water heater in by-pass first, and the hot water pumped directly to the inside shower. By the time the water passed through all the pipes, it was cool enough to take a very comfortable.... very very quick Navy shower. You are limited only to the size of your container that hold the water. Tuck this idea away for a future emergency and hope you never have to do it.