In reply to TYPE FOR PEOPLE WITH LOW-VISION:
robot_type "...so it would be signage and large format graphic panels. "
That's great! Size is a huge thing to all your reading groups.
And Clearview is a great choice for road signage, (your link is broken JM?) but these reading groups are not any different from "normal" people in that the typeface choice should compliment the topic of the content, perhaps within narrower bounds than a normal reading group, but the selection should not be entirely based on either "readability" or .gov, IMHO.
So... what are the signage and large format graphic panels about?