I don't have a Westfalia but I do haul quite a few different boats on my
Vanagon and find the Yakima racks work just great.  I just took my Syncro
loaded w/ my 17' Canoe through some hellish winds yesterday and the racks
held the boat firmly.  I use a bow and stern line one attached to the front
little loop under the bumper and one through one of the loops under the back
bumper.  I also attach the canoe to the crossbars of the rack with 2" wide by
15' straps from NRS.  Yakima has neat little gunwale brackets that attach to
the crossbars and keep the boat from sliding from side to side (I don't have
these yet but will probably get them before I head out this summer for Alaska
w/ my big canoe).

If you are going to be near Arizona or Nevada around December 6 and want to
join a group of boaters paddling from the base of the Hoover Dam through
Black Canyon and on to Willow Beach (great hot springs along the way), let me
know, we are getting the permits this month.  It is a wonderful canoe trip.

Have fun!

-Loretta
87 Syncro GL
90 GL
17' Old Town Canadienne