I would put the ferrets in a bathroom or safe other room that they have
been accustomed to, with the cage open inside.  That gives them running
room.  Or, you could get those "playpens" and erect it around the cage to
make a large running area for them to use, at least while the babysitter
is in the house.
 
Remember to ferret-proof any area your ferrets will be hanging out in,
and do a test by putting them there while you are there and leave them
there at least for overnight, or you may have a problem - and don't do
this the night you are getting on the plane, or you might be spending the
morning hours trying to figure out where they are hiding in your house...
 
Finally, remember that they are clever and if given enough time they may
try rather dangerous acts to get out of a room if left for a long time,
due to their instinct of always wanting to go into the "other" place.
 
Also, if your friend has not had experience with handling them, show them
how with supervision, because you never know when one of your ferrets
will need to be transferred from the cage into a carrying case and to the
vet (and provide an emergency transport case ready to go with litter and
food for this occasion!), plus your babysitter may not have a clue how to
get a cage closed when ferrets are trying to sneek by without possibly
pinching their poor little toes...
 
Last, if this seems overwelming, just keep the ferrets in the cage they
are accustomed to and do not worry about it.  Add a few new paper bags
for them to play in for fun, and they will likely be the safest and most
content, provided there is PLENTY OF WATER, FOOD, and a CLEAN LITTER BOX.
 
Remember - do a test run while you are in town, and good luck,
 
Mark H.
[Posted in FML issue 4888]