Hey all, some exciting news!
Over the past couple years there has been a major mod in the works by a number of community members, called SRB2 Kart. It is a fantastic mod that is worth trying out.
Check out its release thread here
It is primarily a multiplayer mod, but there is a 1P mode that has time attack ghosts. The mod is just as customizable as SRB2 itself, so anyone interested in trying to make levels, characters, or anything else for it is welcome to do so. I highly encourage trying out this mod.