Can an Xterra carry 2,000 lbs of cargo? Haul, not tow.
Will that measurement work with the Daystar spacers/shackle setup? If I AAL, how will that impact my shocks (right now they are stock non-OR so I'm worried I might over-extend them)Given the age of your X you're probably in need of new packs (by the way, leaf packs are the same across all Xterras). Best way to tell is to park on a level surface and see how high the rear is - should be up to half an inch higher from ground to fender than the front. Anything less than level and you're sagging.
If you want to stay on the cheap, you could try an AAL, then swap them to new OEM leaf packs later.