Hola Leo!  Perhaps I've mentioned this before but...now that you have
minimized the voltage drop to your harness connectors you have overcome the
'intensity' part of the equation.  Now you just have to focus on the rest.
If you have the 'boutique' DOT rectangular unique-to-vanagons
lenses/reflectors, adding more intensity really won't do what you have in
mind.  Rather like pouring coffee into a drunk,  wide awake now but still
drunk.

If on the other hand you have Euro Code or E-Code rectangulars you can
upgrade to 80/100W bulbs and have a very significant improvement.  Aiming
these reflectors properly will give you a very useful wide dispersion low
beam.  The high beam is of course rarely used except on dimly lit byways but
it too will be much improved.  The key is to have a high intensity low beam
that does not dazzle oncoming traffic or the rear view mirror of the car in
front of you.

My system uses two 7" round sharp cutoff reflectors mounted in pre 85 round
buckets with the h4 80/100w bulbs.  With a well made reflector/lens
assembly, additional driving lights are rarely needed.  In a pinch the 7"
can be readily replaced at local FLAPS with a standard headlight should one
of the reflectors be damaged.

The object isn't wattage but light intensity where it does the most good.
Since the vanagon headlights sit significantly higher from ground level than
on most cars and since the aiming points for most 7" reflector systems are
fixed relative to high and low beam, properly aiming the low beam will give
you a slightly depressed highbeam hotspot.  No free lunch here.

The end result is better illumination on the road and to the sides, good
reflector/lens assemblies are the most effective way to reach this
objective.  Adding more 'lumens' or light power to good reflectors makes
them brighter but still retains their dispersion or beam pattern.  Adding
more lumens to poorly designed reflectors makes their design flaws even more
evident.

Cheers,

pensioner