[scottj]

A spacer would do the exact same thing as screwing the adjuster tighter by the same amount. If your ride height is OK and you add spacers or screw the adjusters tighter, you will raise the ride height by the same amount. If you install longer springs you would have to back the adjusters off to the same amount of gap as the shorter springs had to retain the same ride height. Afco has take-up springs that go between the adjuster and coil spring to take up the play. They are a 2-1/2" ID flat wound spring that doesn't affect the rate.
Scott

Re-reading your post, is this the type of "spring-spacer" you're refering to?