Despite problems some have had with "stop leak" products, I would add
two small bottles, or one large one (the Vanagon's 4+ gallon capacity
requires the larger amount), of the Bar's Leak liquid for the trip
home.  I've used Bar's for many years on many cars, and it has never
caused a problem.  If your leak is at the "drop" magnitude, you have a
good chance of stopping it this way, and then you can flush and fill the
system after you get home if you don't want to keep the Bar's in there.
Personally, I have it in all my cars all the time.
http://www.barsleaks.com

If you decide to push on and do nothing you should be okay, just keep an
eye on the level and keep the overflow tank full.
--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)

Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Parts cars:
'68 & '73 MGB, '67 MGB GT