If you slide the seat off the rails and place it on the ground outside the
van, installing that battery is lots easier ;o).

Just take a look at the little retainers on the seat rails.  Lift em out of
the notches and pull the seat out.

The major problem once the Optima is in is clearance for the upright
terminals.  Harald and Nancy have an elegant solution for that installation.

Since the optima doesn't leak and is pretty clean and can be used as a
portable power source perhaps leaving it unmounted and  portable allows
another facet in your camping repetoire.  Just set it on the floor behind
the driver seat and charge it from there.

Just put a fused connection to the main battery and charge the optima while
you drive with conventional charging cables.  I personally use a smaller set
designed to jumpstart motorcycles.  They have an 8AWG cable size and battery
clips, plenty enough for charging the Optima.  And you have the advantage of
portability outside the Vanagon.

pensioner