right-aligning figure numbers in table of figures

This is not about right-aligning page numbers, but right-aligning the figure numbers in a table of figures. For example, this is what I get. The numbers left-align with a space between the "Figure" and the <number>.

I have a meticulous client who expects the list of figures to line up on the colon (:), thus producing a variable space between "Figure" and <number>. I can get the text of the caption to line up properly, and I can get the second line of a long caption to line up properly under the first line. What I can't seem to do is get the numbers/colons to right-align.

In the body of the document, here is my definition for a figure caption (there are two -- one for starting the series and one for continuing the series, but other than that they are the same):

In the number field, I have Figure<space>^#:^t -- which produces "Figure<space>9:<tab>Make sure..."

As shown in the image, I have tried to insert a tab between "Figure" and ^# both manually and from the pulldown -- but InDesign displays an error that tells me this is not permitted.

Here is the paragraph definition for the Table of Figures:

There does not seem to be any way to insert a tab here, either. Simply setting a tab in either definition doesn't do the trick if I  can't put the tab character in the numbering of the figures -- except at the end where ID permits it.

I have told my client that I can't do this because of an InDesign limitation... and they are not particularly gruntled, but they've let it pass. It bothers me that I can't put a right-tab between Figure and <number> and have those numbers right-align in the table. After all, I could do this if I were setting type by hand, or pasting it up with a waxer. Is there any other solution to getting the figure numbers to right-align?

Thanks.