One thing I forgot and didn't remember until I saw mention of it this
evening, was that currently many of the super/mega/ultra yachts have
what's known as a "shadow boat" that accompanies them wherever they go. 
Often, this is designed and built when the yacht is, or sometimes
modified from an existing design (how gauche!), and it carries the
helicopters, larger tender boats, submersibles, cars, SUVs, ATVs, and
all the other assorted extras that the owner might want or need (having
their own ground transportation would be, IMO, a big plus because you'd
know it wasn't messed with).  Some have a rather extensive medical suite
aboard, equipment stores, even extra fuel for the subordinate craft,
helos, seaplanes, etc.

In Traveller, you could do the same thing, though given that there
really isn't a cost discount when you design a freighter/utility ship as
compared to a yacht (other than fittings), it might be better in the
long run to take that 5k dton yacht and push it to 8k dton or 9k dton
and add the shadow boat features into one hull.

--
Kurt Feltenberger
xxxxxx@thepaw.org/xxxxxx@yahoo.com
“Before today, I was scared to live, after today, I'm scared I'm not living enough." - Me