I found the release tab. It's right at the back, just before the end of the plastic harness cover. You need to press down on the 1/2" long release tab with a long flat head screw driver. It releases the harness, which will give another 1/2" of room, which was more than enough.

The fuel rail went easily into place, and tightening the bolts slid the rail down over the o-rings easily and smoothly.

Here are some pics of the tabs you need to release, to make fuel rail access and install easier

Front and middle tabs

Rear tab.