Just a quick update - having read this thread and the mention of the Barcelona option, I emailed for an appointment and dropped in to get the visa on my way down. It took less than 20 minutes, including form filling, cost €100, and the lady was nice and friendly. Documents needed - passport and some sort of ticket - I had the email confirmation printout from the Almeria>Melilla ferry. I imagine anything would do...

Point to note - she said that if passing through Ghana from Cote d'Ivoire, I may have trouble using the visa to get into Togo since, even though she marked mine as 'Plusieurs' on number of entries, they may insist on rules that say it should be single entry to the group of countries.

Passing mention here:
https://www.veganwithoutfrontiers.co.../03/barcelona/

Also, definitely check the consulate website and make a note of the address - its on the 1st Floor of an old office building with no signs outside!
Consulado de Benin en Barcelona
Consulado de Benin en Barcelona

Another user, I use it regularly and post it from France (3h away by road) and it's returned within the week!

Previously crossed from Togo to Ghana to CI with it without a problem on the Ivorian border!