Like many people using the Kitbag, I used the Raven Vanguard trigger cover with whatever pistol I carried in it. However, I like to mount a light on my pistol too and to cary in the Kitbag, I had to either rig up with some sort of holster or carry the pistol without any cover on the trigger.
A couple months ago I posed a question in another forum as to the availability of a Vanguard style trigger cover that was compatible with a rail mounted light. From my post, I got a response from Mike at OEM Holsters, http://www.oemholsters.com/index.html.
I ordered one trigger cover for an M&P9C/TLR-3 combo and Glock 19/TLR-1 combo. Both fit perfectly and integrate with the Kitbag just like a Raven Vanguard.
A picture of the M&P9C/TLR-3 with trigger cover in the Kitbag:
Mike does excellent work and has some of the best customer service I've ever seen. If you're looking for a trigger cover, he make them for a wide range of pistol/light combos and can be reached through his website.