FWIW, we have a CCC of just over 300 lbs. While certainly not desirable, it has not caused any issue or forced us to carry any less then we wish. I do try and not travel with full tanks but do on occasion. Not all CG's have dump stations which means after extended stays full waste tanks and partial fresh at times, maybe 400 lbs just in liquids. Ideal for the 2 of us would be more like 700lbs of CCC, but it is what it is. I was watching GVWR like many do to try buy a trailer to fit an existing too small TV. Didn't know about CCC, or much else at the time.
At the start of a trip I have maybe 3 gallons in the black, nothing in the grey, and half a tank in the fresh. Roughly 15 gallons or 120 lbs. Once in a while if staying at a local state park the fresh will be full.