Jobo once made a 10m 70mm reel.
But you would have to use their upright standing tank with reel-twisting agitation.
Jobo once made a 1.6m 70mm reel for their 2500 drum system.
When using longer film one could do blank exposures at the intersections and cut the film in the darkroom.
But that would mean letting go the advantage of doing quick, hassle-free, long serial exposures.