It's just about as simple as you are picturing. One thing, is almost every leaf spring I've installed is a bit "too long" to just stuff the second bolt through.
Really helps to have a sleever bar, round punch or just a big phillips screwdriver to bar the spring eye into line with the mount or shackle.
Only do higher rate springs if you do all 4. Many campers are borderline overloaded before adding all the gear and stuff. If that's the case, then it's a solid recommendation. If not, then yes, too stiff of springs will just cause other difficulties.