On my last camping trip I used a front rack with panniers on the front and a nelson longflap on the back.
I decided if I wanted to carry more for a longer trip I'd put a small rack on the back, remove the bagman, use the same small panniers on the back with the longflap and strap sleeping bag to top of small rack on front (I've carried it on there before). That would free up most of one small pannier for more food and another item of warm clothing.
That's tent camping, mind you, with tent, stove and everything, including change of clothes and a towel for a shower.
For B&B travel, I reckon a Nelson longflap or two small panniers would ample, particularly if you could have a barbag for a camera or food.
Having panniers on the front meant I could stash food for the road somewhere easy to reach. A barbag would be better.