Water tank fill when closed

FWIW, I tried a different approach to the "fill while closed" problem. First using Harry's drain valve solution, I found it works great but takes too long, due to having a 40-gallon fresh water tank in place of the standard 20 gallons. I tapped into the regular gravity-fill line just short of the tank entry point with a plastic tee fitting, then ran a 5/8" line off that through the floor. This line exits in the same area as the other forward drain lines. A garden hose on-off valve was attached below the floor. Standard garden hose end covers keep bugs and dirt out of the line. It worked great the one and only time we have used it. Fills 40 gallons in about two minutes with good pressure. You know it's full the same way Harry's system works; the vent line squirts a little. Your curtains get a little wet if you don't remember to open them before closing down.

My TM is an 06 3124KB. Don't know if the fill pipe is different on other models, so this may not be applicable...

Think I may have gotten a little optimistic about fill time in the above post. On reflection, two minutes can't have been correct to fill 40 gallons. Suffice it to say, it didn't take long to fill the tank; it was akin to running a garden hose at normal rates. Sorry if I misled anyone.