Rather than adding an aux deep cycle battery to a westy, how about just
replacing the starter with a deep cycle?

As I see it, the advantages over adding a second battery are:
Usually when you add an aux battery, only the fridge is hooked up to it.  I
don't really care to run the fridge off a battery.  What I mostly care about
is extended capacity for the 12v dc ports, all of the interior lights, the
stereo, etc.  It seems like changing over all the wiring for this stuff
could be a pain.
Won't take up any extra space.
Maybe I need to replace my starter battery now anyways (hint hint.)

Disadvantages:
You can still run down your battery.

But I figure the point is that it will take longer to run down your battery
this way.  And I always travel with a little jump-start battery anyways
(just in case), so if need be, the deep cycle could just be jumped.

So, what's up with this idea?  Worth doing? Or should I just bite the bullet
and rewire all the lights/power ports/etc to an auxiliary deep-cycle?

Thanks,
Wes