The most important thing to consider is not to reduce or cover the reflective part of the road cone. Many Maxilites are fitted to the bracket and then put on a cone with the lens down, it must point up.
The Maxilite, and other JSP lamps, has drain holes in the bottom so that moisture can flow out and not affect the circuits.
If the lamp fills with rain, not only will it go out but it will also be obscuring the reflective sleeve of the cone.