By bending it out I believe it means bending the flange towards the exterior and not the interior of the car. But is this supposed around the entire aperture?
It seems to play a little havoc around the gas struts which causes the upper tailgate to not always want to close.
Is that not what i said, bend flange OUT. What you are doing is forming a channel for the water to run down so it does not run under the seal where it clips over the boot aperture. Technically the only place that needs doing is the bend area where the lower and upper tail gates meet. That is where the water gets in.