[whpalmer4]

It won't give you a perspective, but you could use Rob Trew's Where in OF to show you all of the tasks which start on a particular date (or range of dates). It would give you a list of the projects which contain those tasks, you can select some, all, or none of them, and then it brings up a view focused on the selected projects, with the matching actions selected so they can be easily spotted. Trivial to then bring up the inspector and set the flag for the bunch.

A typical search you might use for this might be:

tasks where (start date ≥ <dte1>) and (start date ≤ <dte2>)

(the script will prompt you for values for thing enclosed in <>)

The intermediate results of the search look like this: