I ended up more confused than not, particularly where it was mentioned that the gauges have to be inverted in the Y-axis

not the gauges im self but the alpha texture of the gauge i think you talk about

ya for some raison the alpha texture must be up side down to apear corecly in  the sim i have some good tutorial link for you if you whant to learn to made a back lighting panel here the link


          http://www.freeflightdesign.com/tutorials/VC_Lighting_Tutorial.zip

good luk !