I can't stand-in for VEIL Guy
, who will, undoubtedly, be here, shortly, to render his professional opinion.
But I'll give it to you how *I* see it.
In using a "smoked" cover, it should help bias the color of G4 more towards the gray part of the spectrum. As a single, thin, coat, G4 will appear more bluish. I don't know the color of your vehicle, so you're going to have to decide which better suits your overall aesthetics.
With a dual-coat, front (outside) and back (inside) of the cover, you may find that a "smoked" cover would effectively be too dark, particularly at night, if you do not supplement your rear-tag illumination with higher-wattage bulbs (or perhaps even the new-generation, "high output," LEDs).
Dual-coat, front (outside) and back (inside) of a clear cover would likely push the color of the G4 more towards the gray portion of the spectrum than blue, and it would again be up to you to determine what looks best.
The On-Track LaserShield has been shown to, itself, not only "diffuse" incident LIDAR, via its highly "stippled" outer surface (so yes, be careful, there is a "sidedness" to the LaserShield, and you should take care in installation to maximize benefits), but it has also been shown to attenuate IR-spectrum light. Thus, supplementing it with VEIL can effectively be compared to putting a trauma plate in a bullet-resistant vest - the sum of the parts is greater than the whole, and your protection is more than doubled. However, the LaserShield, in being "stippled," will also make your license plate look somewhat "hazy/fuzzy," and this, combined with either too much VEIL (i.e. VEIL front [outside] and back [inside]) or when combined with an overlying cover also dressed with VEIL may produce an effect that may garner you more enforcement attention than you'd otherwise want to elicit, based solely on plate visibility alone.....
My personal preference is to, first and foremost, simply avoid the enforcement stop.
In this being the ultimate goal, I simply don't want any of my countermeasures drawing any more attention than it has to.
With that criteria in-mind, I would, in your shoes do any of the following:
(a) LaserShield + one (outside) layer of VEIL - likely the most technically effective of the proposed solutions, but also the one most likely to attract enforcement attention due to slight visual "distortion" (that's an inaccurate word, and I do apologize, as I truly don't know how to say what I want to say....in-fact, there will not be any "distortion" to your plate, it'll simply appear "fuzzy") and the darker color
(b) smoked cover + one (outside) layer of VEIL - likely the most aesthetically pleasing, if you have a darker vehicle, either with graytones or in black, and it is also likely to be slightly more effective than (c), due to the slight cut-down on total light transmittance from the already "smoked" cover....however, this is also its greatest weakness, as the combined darkness may elicit enforcement attention
(c) clear cover + one (outside) layer of VEIL - likely the most aesthetically pleasing, if your vehicle is of bluish hue, and it will also be the least likely to elicit undue enforcement attention
By now, you must be questioning why I only advise for the outer layer of VEIL.
As per VEIL Guy
's advice, it's the first layer of VEIL that does the most, in terms of performance, at the least trade-off for visual-light passage.
Subsequent layers, while adding to the overall capabilities, also takes a bigger toll on VISUAL light transmission - more important with lighting unit applications, yes, but this does have implications for covering one's license plate.....