Hello, I hear that vanagon outter front berings do go bad now and then.
What I would do , if I was going where you are going, is to buy a couple
replacement berings and just replace them before hand. These can be gotten
from a local flaps.$20. Just pack em w/ grease,and put them in.A brake shop
or local garage can do this. Even on a vasnagon. 1 hour for both. First
though, grab a front wheel by the top of the tire. Shake it back and forth
(this is kinda like kicking tires)If you have any play or slop , your
berings are out of adjustment. Maybe this is your problem. If so, just
repack the old beringds and re adjust by turning a big nut.Take a couple of
replacement berings along just incase. Grease too!   As for the rear noise,
it sounds more serious. Sounds like CV axels are bad. If so, when you hear
this noise , you may only have about 1000 miles left in them. To determin
if these are going bad, get an assistant. Have them listen, while outside
of the van, while yu drive slowley in a tight circle. You will hear a click
click click. Then turn the other way and again drive in a tight circle.
Listen.Once again this repair can be made before yu leave. CV axels can be
had locally at a flaps, and have a garage install them.Even on a vanagon.
Sorry, but this repair will cost $450 for both axels to be replaced by a
shop.Have thisshop go over your van and check for any obvious defects that
willalso have to be replaced.Lastly, take the vanagon rescue squad web
addresswith you .