YES I can.
Crawl under the left rear corner of that 3485. Right beside the left stabilizer you will see a hose hanging down with a cap on it. That is your low point drain for the freshwater tank. Just remove the cap and it will drain.
Here is a modification I made so as not to have to crawl under..
The photo isn't all that great as it makes the MOD look like a sloppy job but it ain't and it does work great.
With all the changes Montana makes every year it is a wonder they never came up with a better idea than having to crawl under the rig to drain a tank. In the past couple years they moved the hot and cold water drains into the convenience station but never thought of relocating the FW drain.