That was I did for my first campaign with HRE too for the same reasons. For almost 5 centuries was I in permanent war with Denmark, Venice, Poland, Hungary and Milan, no matter how strong I was in some periods of this time they would not talk about peace at all. Their "priorities where always "Uknown" and always rejected my cease fire offers.

Now my second with Byzantium is on h/vh. I thought that the battle AI is pretty good and if it was supported with a good campaign AI (better army composition) it would make a very hard challenge for me. Playing at hard not only the AI chose itsa army more wisely than in medioum, but it acted wiser and in diplomatic fields. In fact it acted and that matters as in medioum it seems that the AI does not act diplomaticly at all.

Example: I have trade rights with Venetians. I know that they and the Turks ar are my greatest threats so I keep a diplomat near Venice and a Spy in the borders with Ragusa. After 20-30 peace turns my spy reports a stack coming down from Dalmatia to northen Greece. I send my diplomat to check their intentions. "War" was their priorities and they where not accepting any of my small gifts which would upgrade our relations. They attacked and won 2 small battles, and I 1 but then our big stacks clashed together in one great battle which would determine the balance of powers in the Balkans. I won. Until then their priorities was war or uknown. After that it became "peace". So they accepted a cease fir that lasted until they made a huge army.

Turks on the other hand I have managed to never attack. I constantly offer them small gifts to keep our relations from droping below "poor" and they stand in place even if I have sometimes small garissons in my frontier settlements.

Now I thing that the medioum campaign must include a "dummy" opponent AI while harder a "wiser", althouth I heard that on VH there are no negotiations like in M.