The routing of OSMAnd+ is limited to a few hundred kilometers. On holidays I do do longer trips.
OrganicMaps should still have the contraction-hierarchy routing which scales better for longer distance routing.
But with regard to planning long car journeys, there is always the option of generating the route using one of the several OSM-based routing engines on the web, then downloading a GPX file, opening it in OSMAnd, and telling OSMAnd that is the route you want to follow.