So, I've been following this build for a while now, and now that you're on a project that I actually know something about, I figured that it's a good time for me to chime in.
I work for a small light jet manufacturer as a harness designer, designing harnesses and large gauge power feeders for use in aircraft.
For harness support, we always use P-Clamps of the mil-spec family MS21919. For elongated clamps, if necessary, we use parts of the NAS1714 family.
For tieing bundles together, we usually use waxed lacing cord, or we wrap the bundles in self-fusing silicon tape, and put a zip tie around that. (The tape is to prevent long-term chaffing damage. It's overkill, but we work with flying death cigars. Overkill is good)
Either way, we tie bundles together at least every 6 to 8 inches.
Frequently, it's more like every 3-4 inches when using lacing cord.
On installation, the harnesses are usually supported via p-clamp or cable tie mount (look up Click-Bond for some very interesting products) at a max of every 24 inches, though it usually ends up with a support every 10 inches or so.
Additionally, whenever we have 2 bundles that must be kept separate, but that follow the same route, we will usually use 2 p-clamps butterflied off each other. This method is also used for securing harness bundles to things like hydraulic tubes.
Another factor to be mindful of for long-term longevity for any wire or cable is bend radius.
The usual rule of thumb we use is a minimum radius of 6 times the diameter of the largest cable or wire in the bundle, as measured on the inner radius of the bundle. (10x is actually preferred, but in practice it can sometimes be a hard number to hit)
Finally, for cables that need to move in the manner you are looking for. Normally we would never allow it haha.
I would consider using a coil though. Come off the chassis at the lower apex, circle the cables up 1 or more times as necessary, and return to the drawer at the bottom apex. The bundles would have to be tied as a pair throughout the coil so as to maintain shape, and be secured at both chassis and drawer side with a clamp of some variety.
If needed, clamps can also be installed at the upper apex of each coil that has a metal cable or spring secured to the roof of the compartment so as to help the coil maintain shape and to support the weight.
That's my 2 cents at least.
Good luck with the project. I look forward to seeing the outcome.
how do you fasten a "bundle" in these? wire ties?
didn't matter what anyone was gonna tell me, I needed to learn the idiocy for myself.. (and they knew that.... 
