Hi,
GPS; "GPS map for Morocco from Garmin" it'll be interesting to hear of your opinion, I opted against and took the olaf maps on my 60csx I picked some excellent stops/info not on paper maps. However I found both the Michelin 742 and the rough guide version were very good for detail, and the larger scale insight map better for road navigation. Morocco-overland site/book of course as well, great stuff.
Split charge and fridge, excellent ideas, most "proper" fridges shoudn't draw more than 0.5amps per hour, however if the weather's hot and fridge full, it will effect it hugely, I had some days well into the 40's and my engel was struggling to keep it really cold after parking up for much more than an overnight stop (my 2nd battery is an 85AH and in cooler climes it'll run for 3/4 days), think about getting an insulating jacket for it, it'll help not sure how much though. There's enough shops and some very good supermarkets out there, so don't take too much fridged stuff from uk. If needs be just run your engine for a while.
Solar panels are getting better and smaller, I took a cheap maplins one and could attach to either battery, but didn't need to, so not sure how well it would work.
I speak a little Arabic/French/Spanish, but most people spoke English and were happy to practice it.
Enjoy it, it's a beautiful Country, going back myself in October.
Cheers, Mark