So I tried for an hour to get the rear cable through the grommet but couldn't do it. I barely got it through the metal base of the grommet with a zip tie scratching the cable in the process, but I can't even feed a zip tie through the grommet it's too tight.
The left grommet is the one I tried, its full of wires, you may want to try the right grommet as it only has 1 wire and more space. I'm going to take it to a shop to get it finished since I can't even get the grommets to back into place. It doesn't help that I don't have a garage and its 35 degrees here.
Also, is it possible to get another set of replacement VHB tapes for the front and rear? I managed to mount both of them wrong before wiring them, as I wired them too close to the headliners with not enough room for the actually mini usb connector which are thicker than expected.