I measured my clearance height on stock shocks (on 27s), then installed and adjusted the E1s to same. Seems fine, though they tend to squeak at times. I spray dry lube on them occasionally, which helps for a while.
I answered their questions about cargo weight etc as accurately as I could. When I first got the Elkas I installed them as is. Too low and too soft really, though the softness was nice when the terrain was reasonable. But I was bottoming out the shocks and skid at times; was lower than stock height, and softer. All good now.