Currently, the effect of DRL (Daytime Running Lamps/Lights) on police LIDAR remains a great unknown.
Although we've see, recently, that both HID headlamps as well as various traditional halogen-incandescent headlamps, in DRL use format, can cause rather unpredictable responses on current-generation police LIDAR devices (anything from delayed lock to eliciting error or even spurious jam-codes), the biggest concern is that none of these one-off instances are consistently manifest, and as-such, no-one should count on these effects/observations for any kind of true "countermeasure."
In terms of DRL or other such lighting reducing the efficacy of VEIL and/or other passive protective measures, that is, to the best of my recall, an area which has not yet been tested in the independent, enthusiast/hobbyist, community.
However, given the way in which police LIDAR works, I truly doubt that there's any negative effect or degradation of performance, in terms of the VEIL. I believe that you'll get just as good protection, whether or not your vehicle utilized DRLs.
RE: DRL -
Check your specific vehicle's on-line enthusiast Forums.
Depending on the vehicle, "deactivating" DRLs may be as easy as pulling a plug or snipping a wire, and in many cases, can also be easily re-enabled, and also will not elicit any CELs/DTCs ("Check Engine Light warning").
For both of our Subarus, for example, it's a matter of simply unplugging the relay. In my '05 Legacy, this relay exists inside the cabin, near the cabin main fusebox. In my wife's '09 Forester, this relay is in the engine compartment, near the passenger's side foglamp housing and the intake airbox resonator.
This is not information that your dealer will give you. It's akin to having them rip out (one of) your vehicle's cat(s). They're not going to tell you because they're forbidden from doing so.
However, this is something that many in the enthusiast community may know where to look, and what to do.