Man dude(s) the solution is just right infront your eyes just vote here:
https://forums.zwift.com/t/route-creator/2449
https://forums.zwift.com/t/create-custom-shareable-routes-for-zwift-courses/13907
https://forums.zwift.com/t/creating-own-routes/13521
https://forums.zwift.com/t/create-own-custom-route-and-follow-them/13669
https://forums.zwift.com/t/create-our-own-routes/14301
https://forums.zwift.com/t/multiple-route-option-commencement-of-a-ride/14183
https://forums.zwift.com/t/ability-to-change-starting-point-to-create-critical-mass-we-are-limited-to-the-map-we-ride-but-it-would-great-to-be-able-to-change-starting-point/14350
And/or make some suggestions here: