I'll be upfront and say that I do not like spacers. In a more complex answer to your question, for a leaf spring Montero, you could run a Montero Sport rear axle with disc brakes...is already a slightly wider stance. For the Gen I coil spring, simply replace with a Gen II axle.

Another consideration is the brake system. I did not like how the 32" tires stopped. The wide tire was allowed to wallow around by the narrow stock rim.

I have a painted set of the 5-hole rims that I've considered having rebanded and chromed. This would allow me to control the backspacing, have the 'look and feel' and utilize wider tires.