pre-installation adjustment of Koni HD SPX shocks

I understand that you probably want to save time by only setting them once. I Can't tell you the best setting and in any case its also a matter of personal taste. I suggest you set them to a low setting and try it out. (From experience of similar Koni's, even on the softest setting they are likely to be substantially stiffer than the original Sachs. The clue is in the 'HD'.) Your requirements mention both highways and rock-crawling. The former is better with a stiff setting to avoid too much body roll in cornering, and the latter a soft one.

I can understand you wanting to preset the rebound rate prior to fitting the shocks because the adjustment is made by twisting the lower section of the shock which means it can not be done with the lower mount attached.

In general there are about 2.5 full rotations of the adjuster from soft to hard or five half rotations, which is the unit Koni use.

From experience I would go with as soft a setting as possible for off road driving and as you correctly said a bit firmer at the front. If you try half a turn at the rear and two half turns at the front (starting from the fully soft position) that should give you a comfortable and tractable ride off road. This assumes that you are running on standard springs.

You can firm the rebound rate up if you find tarmac handling too soft but then your off road handling will suffer on the corrugations you mentioned. I set my G up for a supple forgiving ride because it is a 3 ton brick with a ladder chassis at its best off the tarmac and I didn't want to compromise that.

Doug.