Not sure what you mean by "Serious Camping." I regularly go to BMW rallies and camp out, but as I tell people that isn't REALLY camping, it's "Sleeping in a tent." I don't have to carry anything but my clothing, tent, sleeping bag and toiletries as everything else is available at the rally site (food, electricity, showers, etc).
That being said, I manage to pack everything for a solo rally trip using just the underseat storage of my C650GT and the top box (nothing lashed to the seat or outside the top box). You just have to choose your camping gear carefully. I buy my tents based on how SMALL they pack rather than how big they are when fully set up. A lightweight three-season sleeping bag packs smaller than a heavy, four-season bag. Inflatable pillows pack smaller than regular pillows, etc.
Microfiber clothing packs smaller and dries faster than regular cotton or polyester. I always pack three days worth of clothing plus what I'm wearing and do laundry every third day. My Aerostich suits (Roadcrafter or Darien) save me from having to pack a rainsuit as well. All these things add up.