Can't help on the solo bit as its always been the two of us travelling but I'm sure a lady of your travelling experience around Europe and into Morocco will hold you in good stead for the trip.
Route wise we've always found the best way is via Belgium, Luxembourg, down through Eastern France via then into Switzerland via Basel then into Italy to Milan. Then either turn left for Venice or straight on for Ancona. Mostly toll free until Italy and of course the Swiss vignette assuming you are now under 3.5t.
If you think you'll be comfortable with aires and wildcamping along the way then I can list you places we've used over the years for the above. Can't help with campsites but that would depend on time of year you are going.
Ferry wise for Greece, you will probably have to wait until the new year before any firm prices are published although Superfast have put a few prices on their website.
Pay careful attention to the dreaded fuel surcharges, especially on the Venice route where they were very steep this year (50euro each way for a camper +1pax
) and are usually hidden in the smallprint.
If you're landing at Patras, looking at the map and assuming you're getting a further ferry from Killini, its only a relatively short drive between the two so you probably wouldn't need an overnight for that stretch. We have wildcamped along that stretch though, so can give you more info if req'd.
Its 2 years since we were last in Greece and then it was only to transit through the north to Turkey so maybe a little out of touch with the situation out there but I would contact Margaret and Barry on the magbaz website who visit regularly, they are very helpful and would be who I would ask for advice.
A snippet about the current situation and security inGreece taken from their website...
Give us a shout if you need more help.