The only way around your issue (and I too am on PS3 and have had it) is to save the character out to my online storage or to peripheral storage (usb, harddrive, etc...) and then delete them and then reload them when the time comes for you to start using them again.
Someone said something about turning DLCs on or off on the main menu and I have never seen this option.
If I want to play without them, I just delete them from the PS3 and then reload them when I want them again. Fortunately they are practically eternal on the Playstation Plus network (of course you could always save them to a periphery as well if you wanted to).
I got mine digitally long ago, so perhaps the disk works differently, but I doubt it.