I had my Alcans built for 500# and it took a while for them to settle in.
Put the 700# load in there, and leave it in for a few weeks...sandbags, water, gym weights, whatever. Once I did that with mine (actually it was a 1200 mile road trip with 1000# in the bed plus tongue weight of the trailer), they were pretty good. For the first few months after I got them and before I broke them in they were stupid stiff.
Load it up, forget about it for a while, go cycle the suspension in the dirt, they're not gonna sag much, but they will break in if that makes any sense.
If you have a 1st-gen Taco you should be able to run GVW 6500# with about a 50/50 weight distro, offroad, without breaking anything (unless you trade skinny pedal for skill). Go do that a few runs, they'll feel better!