so I ended up doing exactly what gudmund did with my sumosprings. When I lifted my trailer, I saw that my leafs didn't have very much preload on them. Less than an inch. Which didn't give me enough space for the sumosprings to fit (even though sumosprings says you need 6" of space minimum, and I had just a hair less than that with the trailer on the ground).
That's fine. Knowing that the sumosprings can be trimmed easily enough, I went ahead and did the same with mine, using a hacksaw.
I haven't set it back on the ground yet. Had to take the wheels off in order to turn the wrench to tighten the u-bolts, and I'm just leaving the wheels off until I get the tires changed. That'll give me a chance to go through the rest of the suspension (esp the shackles), the brakes, and the hub bearings.