Does the JL/Gladiator base sit above the dash?

No.

In keeping with our JK specific mount base, our lead designer worked to keep the base as low as possible. Working hard to leverage the new dash angles and OEM fastener as we did in the original JK Mount™, the new JL / Gladiator Rail™  is as unobtrusive as possible.

The new JL / Gladiator dash line is higher than for the previous JK model and has reduced the useable screen area. Therefore, a key design goal focused on maximum visibility and safety to avoid the JL / Gladiator Rail™ being visible outside the dash recess.