I just learned the Dead thrall spell and one thing that I find interesting (if a little morbid) is to collect the bodies of important people who die during quests (for example Ulfric Stormcloak). One thing that helps with that is that Ulfric's body never disappears. This way I can put him on a chair in my house and know that he will always be there. However, I do believe that his ability to never disappear is an exception to the norm and most bodies will disappear after some time. Is there a way (maybe through a console command or something) to prevent any other bodies from disappearing in the same way Ulfric does not?

I would like to ideally have a collection of important characters that died in the story to have a record of my victories and have them forever. A little morbid I know, but this is a game, not real life.