"outdoor use" only means "don't use in enclosed spaces, or the vapors will get you high".

If you're going to rattle-can the rest of the exterior, I'd suggest using a few layers of silver/reflective basecoat--so whatever you paint over it will "pop" more. If it were me, I'd rattle can a layer of glow-in-the-dark paint over end color--with a couple layers of clear-coat on top. That way, when the sun sets, the VX will "glow".