In my experiance tilting a header tank backwards creates a draw of air in the uat/header tank by sucking air out of the clunk in the main tank. Unless I'm missing something here, he will suck all the fuel out of the header.

Just came across this a few weeks ago losing engine by the header installed with tubing to the rear.

This is from all the down attitude in a typical flight. I guess if you keep the nose up the whole time you won't flame out.

In other words, if you drew air into the UAT from down attitude and then went to the upline with the header aiming backwards, how many times could you do that before the UAT was empty?

With a 2 ounce Header on a Top Gun Mig a few weeks ago, we found that it was just a few minutes into the flight. I mean if the UAT was installed upside down, it would work for some amount of time.