Jay,
Your answers are embedded below:

>There apprears to be some confusion as to the wire sizes feeding the
>refridgerator relay.  In my '85 Westy, the relay is fed by a 2.5 mm2 (10
AWG)
>wire, not an 1 mm2 (18 AWG).

The conversion chart that I have indicates that the equivelant of a 2.5mm2
wire is about 13 AWG; not 10 AWG.

This 2.5 wire comes directly from the battery--not
>from the dash!

The Bentley page for my 90 Westy Syncro shows the wire routed via the main
fuse panel (but not fused)... and that's what the reality proved to be in my
van.

Does anyone know what the rating of this relay is?  If it is
>good for 30 amps, you could simply upgrade the 10 AWG wiring to a 4 or 8.

It is called a 'fridge relay' in the Bentley; not and auxilary battery
relay. The fridge only draws 7 or 8 amps and the circuit was never designed
for an auxiliary battery. And auxiliary battery can draw up to a 70 amp
surge if fully discharged! A 75 amp relay can be had for under $20 I
believe... a $40 amp relay for about $8. The 75 amp relay sold by
Alternative Energy has screw down posts that I was able to fit #6 ring
termanals to with some filing to alter their width. I would suggest a
minimum #8 wire and from that size up I could not find any spade terminals
to fit typical terminals on relays.

Then
>tie in the aux battery between the relay (#30) and the "refridgerator
heater"
>fuse.  I would upgrage this short section to 4 or 8 AWG too.

Basically, this is how it would work.
see: www.vanagon.com for more information

It's tight quarters inside the auxiliary battery box... using marine grade
wire is much nicer since it is VERY MUCH more flexible than automotive
wire... You can order it form West Marine if you don't have a maring supply
place in your area. I used #6 since marine is 10% larger than automotive
wire.

 You would not be
>charging the aux battery through the trigger wire!  Am I right?

That's right.

Bill
>
>                                                        Jay
>                                                        '85 Westy
>