You won't break the rod if you use the drag or back reel. The only way you'd break the rod is if you loaded it with heavy line and screwed the drag down tight. Just use the line the rod is rated for.

I landed a 7 lb. largemouth on 2 lb. line and my 4 1/2 foot UL. I've also caught a bunch of 8-10 lb. channel cats on the same rod but with 4 lb. line.
My dad got a 20+ lb. drum on 4 lb. with his 5 foot UL.