From my limited knowledge of this part of the war it appears that the allied operations (which featured both the Spanish army and a lot of assorted irregulars) were very much designed to tie down the French. The Royal Navy was active in supporting the allies and there was even use of the Sicilian army as well. This would be fertile ground for me as the mix of troops would be suitably eclectic and with actions that would be smaller in scale. Ideal Portable Napoleonic Wargame material and with bags of mini campaign potential.
The Del Prado collection would furnish the French and the British but I suspect I will need to look further afield for the Spanish and others. Something to ponder as a bolt on to the Napoleonic project for next year.