Lest anyone ask, I did read through the whole 4runner Suspension FAQ here:

3rd Gen 4Runner Lift Information and FAQ's

I still have a couple questions, though.

My vehicle is a 99 SR5 w/4WD and 5-speed manual transmission. I've read in some places that the 99 4runners with 4WD sit 1" taller than anything else in the 3rd gen; per the FAQ, it's just the 99 Highlander that sits taller. Can somebody clarify which is the case?

Which brings me to my second question, and really the core of the issue. My vehicle spends most of its time on pavement, a goodly amount of time on unimproved roads (ie, dirt roads and forest trails), and a very small amount of time in true off-road conditions. When on the road, it spends about 25% of its time laden with 300-500 pounds of stuff in the back (tools, air compressor, portable measuring gear, dogs, etc.). About once a month I need to tow a moderate load (2,000 pounds, give or take). This has resulted in rear sag. I think what I'd like to do, then, is achieve the following:
-- Replace front shocks and springs to bring front up to stock height or stock height + 1-2 inches, with shocks rated for a slightly heavier load and providing a firmer/stiffer ride than factory.
-- Replace rear shocks and springs to bring rear up to stock height or stock height + 1-2 inches, with shocks rated for a moderately heavier load and providing a firmer/stiffer ride than factory.
-- Avoid having to replace or re-route anything else
-- Some rake is fine provided the truck is level when loaded and does not sag when loaded.

Looking at the FAQ, it looks like OME makes the necessary components rated for heavier load (the 883/891 combo)-- but at an additional height of 3", which would require a diff drop, which I'd prefer to avoid doing. That said, it seems as though one could also put in an 881 and 906 set and just put in heavier-rated shocks to achieve what I'm looking to do.

So... thoughts? My experience with suspension components is honestly fairly limited, I'm just looking for something to achieve the objectives I've listed without breaking the bank.