What is the L/D penalty of outside mounted GoPros?

I am thinking about trying to do some soaring videos. Inside the cockpit footage only is boring and I want to be more like Balleka with amazing outside camera shots. The reason why I haven't done much is concern over the performance penalty of outside cams while trying to do longer XC flights.

Anyone smarter than me (I know most of you are, other than TT) able to figure out the drag penalty of a GoPro either mounted on the wing or on the tail of a 27? It would be attached with the adhesive mount and not the larger suction cup mount in hope of reducing the drag. The GoPro in its larger case to accommodate an extra battery is 41mm H x 59mm W x 40mm D.

What I am hoping to figure out is if it is a 1-2 point L/D penalty or something more like a 4-5 point drop. Those of you who have flown with me know I need every L/D point I can get.

Here's to hopefully a lot of fun 2015 soaring videos shared from a bunch of us!

Bruno - B4
Oh yeah - and Nephi is amazing!