UAT Header Tank - where?

[DDragon]

Hi,
been doing some research, trying to figure out where I can put the uat header tank and I noticed that a lot of people mount these in the most interesting places (no joke, so get your mind out of the gutter )

Here's a pic of one example.... the tank is between the frames and higher than the side tanks as well as being mounted straight up.

Now I'm wondering, will this work? I guess the pump can pump out the needed fuel, but I thought it was better to have it so that it used gravity as much as possible?

Can anyone shed some light on this?

Thanks.