There is so much, but you have already assembled an impressive body of works. I will probably overlook something important, but here are a few that spring to mind:

Antony Brett-James Life in Wellington's Army - discusses what it was like to be an officer or soldier in Wellington's army, on campaign or in cantonments, drawing on a great range of memoirs &c. Very readable and enjoyable.

Gavin Daly The British Soldier in the Peninsular War - a recent, rather academic but still very interesting book that looks at how British soldiers reacted to their experiences in Spain and Portugal - this will have more on their interaction with local civilians than Brett James, I think.

Daly has also written an article which is very close to some of the topics you mention: ‘A Dirty, Indolent, Priest-Ridden City: British Soldiers in Lisbon during the Peninsular War, 1808-1813’ History vol 94 no 316 2009 p 461-482

Charles Esdaile The Peninsular War - A New History. The best single volume history of the war with many new insights.

Donald D. Horward's full thesis . 'The French Invasion of Portugal, 1810-1811' University of Minnesota, PhD 1962 has never been published but is available - I think from university microfilms, but possibly online now.

There is no overall account of the war from the French perspective giving a proper account of Napoleon's strategy and plans, or of the life of French troops in the Peninsula - some things give you bits of the picture, but nothing puts them all together. It is the biggest and strangest gap in the literature.

A few memoirs to mention as they are relevant to your particular interests:

The Backbone. Diaries of a Military Family in the Napoleonic Wars edited by Alethea Hayter (1993) This is about the Slessor family - a British family living in Portugal before the French invasions, and about half of it relates to 1807-1809 in Portugal. Quite different material from in most memoirs.

William Warre Letters from the Peninsula, 1808-1812 - he was Beresford's ADC and his letters are both very enjoyable and give more on the Portuguese side of things.

(There is also the excellent new biography of Beresford by Marcus Beresford)

I would also recommend:

Intelligence Officer in the Peninsula. Letters and Diaries of Major the Hon. Edward Charles Cocks, 1786-1812 edited by Julia Page

and

At Wellington's Right Hand. The Letters of Lieutenant-Colonel Sir Alexander Gordon, 1808-1815 which I edited for the Army Record Society (Gordon was one of Wellington's most trusted ADCs and wrote long letters home to his brother, Lord Aberdeen, describing Wellington's plans and the prospects for future operations. They aren't very personal, but again add something that isn't covered in other memoirs or letters).

Finally, I hope you know that as well as my published biography of Wellington, which I see you have, there is a website www.lifeofwellington.com that has a great deal of supplementary material, running in parallel to the text. It is freely available to anyone; you can download part or all of the material; and it is broken down into lots of little sections, so that it is easy to find what you are looking for. (At least, I hope it is - if not please let me know).