Horizontal bargeboard extensions

[MIKEY_!]

Please excuse my ignorance! With the new bargeboard regulations this year we're seeing horizontal extensions of the lower edge of the bargeboards at about the height of the step plane, the Mercedes and Ferrari are good examples. The Ferrari even has an extension coming off the T-tray. I have several questions:
1) Are these extensions actually at the height of the step plane?
2) How wide and far forward can they be?
3) If these extensions could be legally joined with the leading edge of the floor itself to effectively make the floor longer, would that be beneficial? In theory a bigger floor area will give more downforce (I realise it's way more complex than that, but this is only a starting point). These extensions could form a flap at the leading edge of the floor to still allow the strong flow around the T-tray to pass under the floor where it usually does. Would that even be legal?

I'd really appreciate some input, this has been bugging me for weeks and I can't find any information on it one way or the other.

[matt21]

All parts seen from below must lie on the step- or reference-plane.
So if you have barge boards which are not two-dimensional, you have to have the extensions in order to make them legal.

[Just_a_fan]

There are a number of boxes in which devices may, and equally may not, be placed. These are given in the F1 Technical Regulations which can be downloaded from www.fia.com.

These locations prevent the joining of various devices to make a bigger floor, for example.