One way to potentially boost range while also achieving terminal precision guidance without sacrificing speed could be to make the shells into mini-scramjets with TVC for course correction.
Such scramjet shells will probably not have much room for warheads, so will need to rely on KE to so most of the damage, so would probably be more suitable for AA or anti-shipping rather than shore bombardment fire support.
Or maybe just accept that a railgun projectile won't be that accurate, and supply it with a dispenser for tungsten ball bearings?
We've seen that video where a hypersonic ASBM dispenses ball bearings. Then it also becomes an area cluster munition suitable for soft targets.
Technologically, that is a lot simpler and cheaper. And they should already have a larger version which is already perfected from the ASBM warhead.