Auto top of that does not use a float swich, pump, or power.

[Richer]

Instead of doing what you suggested... I would suggest using a Nurce-type of contraption for your topoff. Doing so would allow you to use a larger container, and you can place the container farther away from your sump/tank.

Check this link out for more info on how to construct your own auto-topoff.

HTH
-Richer