I have been trying to fix my recent problem with my fuses blowing too, I discovered my backup light switch is/was part of the problem, (same circuit) I would suggest you check yours...I disconnected mine and the problem went away, but I am not one to call it good there.
My problem got so bad, it melted a fuse, fortunately it didn't do any damage to my fuseblock (which, I may end up replacing since they're cheap and used ones are out there). Like you, it started out gradual but the melted fuse woke me up.
I am still trouble shooting but I suspect a short somewhere towards the back of my car, maybe when I hooked up my rear fog?!
Thats my 2 cents anyway.
where would i find htis backup light fuse??