Skeleton Horse Spawn is a minimalistic configurable mod which allows skeleton horses to spawn naturally with a skeleton riding it. Whenever a skeleton spawns, it has a chance to be spawned as a rider. You can configure it to only spawn on the surface and if it should burn in daylight.
chanceSurfaceSkeletonHasHorse default 0.05, min 0, max 1.0 The chance a skeleton that has spawned on the surface is riding a horse.
shouldBurnSkeletonHorsesInDaylight default true If enabled, burns skeleton horses when daylight shines upon them.
onlySpawnSkeletonHorsesOnSurface default true If enabled, a skeleton horse with rider will only spawn on the surface.
You may freely use this mod in any modpack, as long as the download remains hosted within the CurseForge or Modrinth ecosystem.
Serilum.com contains an overview and more information on all mods available. For issues, ideas, suggestions or anything else there is the Github repo. Thanks!