Welcome to the forum! The kind of service manual you might have for a car doesn't exist for RVs.
It's a great suggestion to access Ed Felker's excellent crowd sourced manual for Vegas/Axis. There is a lot of similarities with the Citation. You can start building your own similar manual by downloading the info on each component from that component's manufacturer.
Then do a search on this forum for "Citation" and copy those posts or threads that are of interest to you. If you didn't get a chassis manual for your Mercedes chassis, you can probably download that, too.
Put it all on a flash drive or print out your own big book.
Bad decisions make great stories!