I think the difficulty might be to narrow your interest down to a practical subject, and at the same time one where there are sufficient available sources. One possibility would be to look at the use Napoleon and the French government made of information published in British newspapers about operations in the Peninsula. This has the advantage that many of the newspapers are now available online; and you have Napoleon's Correspondence (including his Confidential Correspondence with Joseph) as an accessible primary source. On the other hand, my impression is that you might do a lot of work only to discover a bit of a mare's nest i.e. that in fact the French did NOT make nearly as much or systematic use of this source as they might have done. Which is useful in its way, but not nearly as satisfying as being able to establish a line of connection. There are quite a few references in Napoleon's letters to news from Spain and Portugal received first via British newspapers (e.g. of a battle fought or armies moving), but I didn't see any indication of careful collation of raw material, (regiments sailing; private letters from the army indicating mood or intentions).
If you're not wedded to Intelligence, there is a wide open field for someone to start studying Napoleon's grand strategy in the Peninsula - how he hoped to win the war, and the level of resources he was prepared (and able) to devote to it - and plenty of sources for that. And not just the Peninsula for that matter. Most histories are firmly stuck at the level of operations, whereas a step back puts everything in a new light.