How to Write Sideways Text for Book Spine in Indesign without Disturbing Color Background?

Question

I'm completing an Ingram cover template in InDesign. The spine must include sideways text (NOT vertical text as in:

S
P
I
N
E

)

First, I used the eyedrop tool to fill the spine frame with an appropriate color. On the Ingram template, the spine include bleed marks on all four sides which have to be filled with color.

Using the text tool, the insert cursor looks like a short vertical line (as in this Superuser text box). Typing text will result in left to right text.

I am aware of the "Write text along a Path" tool. The problem is that:

a) When I create a path using the line tool, the line is visible instead of a guide; and b) When I type text the required background color disappears.

While working on a previous template there was an easy way to rotate the cursor so that text could be typed on (and in) the colored spine frame in the appropriate direction and without disturbing the existing color. Unfortunately, I stumbled on this solution and cannot duplicate my steps.

Does anyone know then, how to simply write text sideways in an Indesign document given the foregoing constraints?

Thanks.