It appears going from the pinch weld out would be the most efficient but would the added space the pinch weld adds between the barge board and rocker panel really matter if ran from the frame rail out? It also seems running from the frame rail out would give more options for mounting.

 

I am not sure about about pinch weld mounting of barge boards due to strength.

Every picture on here I have seen goes from the frame rails (in some way) and joins to the pinch weld.
The issue for all mounting solutions is where you live. Most solutions on here are for the lovely dry california which living in the UK makes them basically rust magnets.

Blackbird has done some very fancy work and others have done some more simple DIY solutions in the threads you will find using the search button.

 

Why would having less surface area for the barge board under the car be more efficient?

 

Agreed. Barge boards are extensions of a flat floor.

 

It wouldn't but both methods have been done by members on here and I skipped CFD for racquetball in college so I'd rather ask than assume. If you want to know about racquetball though I'm your huckleberry.

 

mine are ran from the inside edge of the frame rail out. feel free to look at my build thread.

 

Mine will be ran from the outside of the frame rail. Ill post pictures when i get around to actually installing them