All good questions.
All the information I provided was from Jayco's 1999 product brochure.
UVW: unloaded trailer weight at the factory, but is not
the actual ship weight.
GVWR: maximum weight that the TT can weigh when loaded
The actual ship weight may add another 200lbs-300lbs to the published UVW, which means the actual CCC will decrease.
Yes, the published CCC is basically the difference between the published UVW and the published GVWR.
(UVW 4,200lbs) + (250 lbs account for Ship Weight) + (700lbs for camping cargo/stuff, fluids not included) = 5,150lbs Loaded TT weight
In regards to your trucks 7,000lb "published" Tow Rating, please note that this isn't your "actual" tow rating. The following link will clarify: http://www.jaycoowners.com/showthrea...uot-Tow-Rating
Even though your actual tow rating will be less than 7,000lbs, IMO a TT with a loaded weight (ready to go camping) around 5,500lbs would be ideal (possibly a little higher).
On Edit: The 700lbs for cargo/stuff is a rough "average" assumption, you actual loading habits may differ.