Thanks for reaching out with a great question! We have been pretty divided on personal routes for quite some time. On the one hand, they would be wonderful additions for planning trips! On the other, they might clutter our map as it exists now. Because creating and displaying (or not displaying) personal/custom routes on the site requires a bit of re-imagining of what our site offers, and how it might function, we haven't been able to address this one in the past. However, we have recently increased our bandwidth and we're hoping to be able to take on more projects like this in the near future. This particular question is at the top of mind, and hopefully I will have more information for you in the near future. In the meanwhile, I appreciate your patience.
I can appreciate your bandwidth and clutter concerns. I might suggest some options and ideas -
custom routes are stored in a separate area on the website. It could be tied to the actual main page for a particular hike but the custom routes could be a subsection or a different tab.
custom routes have to be downloaded to our local devices
From a planning stand point this would be huge. Combining routes to create a hike would be very helpful. You might look at UnderArmour's MapyMyRide site to see how custom routes are handled. Of course, it is all user driven in the sense there are no "master" rides or runs that are the basis - everything is user submitted. But at least you can get the presentation aspect.