It's interesting that the stall warning vane is required from Vans for you guys in the 10 & 14. It's an add on in the 7.
The & kits don't come with a stall vane and I don't believe it's even documented as an option on the assembly prints, although I'd have to go to the print to verify that. Even the pitot tube in the print is just the roll your own bent aluminum tube solution.
I wonder, is there not a recognizable buffet to announce the onset of a stall in the 10 & 14? If not, I can see why Vans would want to make sure you had some sort of solution.