You are taking EU by storm Iain !
I said that I'd give you info on some campsites that might be of interest..Albania and FYROM might not end up being on your route but Romania certainly is, and Camping Ananas is perfectly located to have a round trip of the Transfargarasan, if fact I'd say to ride the highway north / south and drop right down on the south side, then turn around after a food stop and ride back up and down the north side back to Sibiu !
You'll get the best of all the views that way and the road continuing south was ( is still ? ) in pretty bad shape, and very slow thanks to Romania building town linear rather than in clusters...non stop 50kmh speed limits for a long way.
Camping Ananas is really chilled but then again Sibiu is also a really nice city to hang out.
https://www.ananas7b.de/en/home_english.html
Camping Rino ( ran by an Albanian called Marino ) is another nice place to stop, has it's own little restaurant selling local food and when you arrive he gives out free Rakia, when you get up in the morning everyone gets free espresso
. What's not to like.
https://campingrino.wordpress.com/
Camping Kranea in Albania is German owned but run by a really nice Albanian family, onsite restaurant and in a really quiet spot on the beach just a few kms from Himare.
And if you do make it there make sure that you ride the coastal road between Vlore and Sarande as it's stunning !
https://camping-kranea.com
So much to see and just not enough time !
Enjoy