As terrifying as it is I have been thinking again. If any of you have built the Top Flite Cessna 182 you may recall the flaps and ailerons have corrugations and top Flite includes an styrene extrusion (I think it is "T" shaped) to glue to the surface before covering. It seems to me if you took a half round or a small "T" shaped styrene stick and applied it to the surface it would provide a base to support the shape of a foil tape, AeroFoil, or FliteMetal applied over it. Half rounds get as small as .040 wide X .020 thick and T shaped strips go as small at .035 wide. FliteMetal is pretty light and AeroFoil even lighter so on tail surfaces where you don't won't additional weight there is an advantage. I have seen scale corrugated rib roofing that might work as well if you want a panel.