What you need to do is order a custom made holster from a customer holster maker. An off the shelf product will not do.
You will need to measure the width of your slide with the grip tape and let the holster maker know so that they can account for the extra width.
With that said, the primary retention on a light-bearing holster would be on the light, not the slide. However, there is some friction between the slide and the holster which aids in retention.
With your pistol setup like that, you should consider adding a 2nd level of retention, such as a hood, to use when you are running and doing ground drills etc.
I would be glad to try to help you out more. In order to not violate the rules of this forum, please IM me or email me if you want to discuss this any further.