Picked up one of these today
<
http://www.harborfreight.com/20-amp-automotive-fuse-circuit-tester-67725.html
>
But BEWARE, there apparently are two versions of this and the 20 amp
version shown in that ad is NOT what you want for your Vanagon.  Although
it might be made to work it is intended for use with the Mini spade fuses,
not with ATC/ATO fuses (the bigger ones).  And it requires a Mini fuse to
be inserted into the probe to work.  There is a 30 amp version that was
hanging next to it at Harbor Freight but I didn't compare them, just
assumed only larger capacity even though the same price.  I'm going to go
back tomorrow and look at the 30 amp version to see if it is for the ATC
type fuses.
Details:  You can jam the probes into the socket for an ATC fuse but just
barley.  And you have to have a supply of the Mini fuses for the probe.
Not really the best setup.  And the HF website is wrong, they say that both
the 20 amp and 30 amp are for ATC fuses, not true.  I hope the 30 amp
version is actually for the ATC configuration.