You can skip cutting another hole in your TrailManor.
Also skip a new switch because you will be inside turning valves inside anyway.
My thought is to first add connector outside to fill tank thru drain.
...... See Also:
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http://www.trailmanorowners.com/foru...ead.php?t=8471
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http://www.trailmanorowners.com/foru...ead.php?t=7484
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http://www.trailmanorowners.com/foru...ead.php?t=4568
Since every RVer carries a long hose, this could be connected out to a bucket, your truck, or a fellow camper who is leaving but has surplus water, etc.
Then add three valves and two tubes INSIDE as shown in this modified drawing:
http://i849.photobucket.com/albums/a...esusingpum.jpg Diagram v1
I'm assuming your TM will be up when doing this, so external valves/switches are unnessisary.
Also make your pipes loop up a foot or so to aid in draining and winterizing.
The pipe show on the left could also connect into the top "bucket fill".
To quote George Wallace “I Be Thinkin’".
Hope this helps...