Really? An optic and a magnifier (or a LPVO in lieu of both) -- plus a PERST -- on a dedicated night gun? Yikes.
If it were mine, I'd ditch any BUIS (if you haven't already), slap the Perst where the front sight usually goes, and drop an EXPS3 up top for passive targeting. (A holosun would do, as well, but I prefer the EXPS3's reticle under nods to the Holosun's, as the latter is entirely too bright for my liking.) i.e. No magnifier, no LPVO, and no irons on my dedicated night gun. My thinking is that at night, any shooting I'd need to do with nods sans illuminator/laser ... would leverage the EXPS3. If I needed to take more than a few shots like that, well, I probably wouldn't be using passive IR targeting capabilities via the EXPS3 for very long, in which case the Perst's IR laser comes into play. In the event that I had to use that firearm under white light (because, say, a big room was entered), I'd transition to the visible laser on the Perst -- since I'd already be accustomed to looking downrange at the target when using the IR laser. In a small lit room a la CQB, well, the visible laser works there or one can point and shoot -- the latter of which is less than ideal but at close range with a rifle or braced pistol, it's pretty reasonable. In the event that all three aiming mechanisms failed (highly unlikely, but crap happens), I'd transition to pistol ... and not be sticking around.
The thinking on the above is that, for the most part, night shots just aren't taken at terribly long ranges -- making a magnifier or LPVO dead weight, IMHO. For those shooters who DO shoot long range at night, they're usually in fixed positions with a night vision or thermal device mounted on the firearm (i.e. not their head) ... specifically to allow good cheek weld while taking those long ranges shots -- in which case the Perst and EXPS3 are dead weight on their guns set up for long range.
I guess I just don't advocate one gun trying to do everything, because it'll just end up doing it all in relatively mediocre fashion compared to dedicated long range night guns and dedicated 100yd or less night guns ... both of which would be set up different from day guns.
Surreal
P.S. Some people keep the BUIS. The trouble there is the height of the irons versus the height of the mount for the optic. Risers supporting the optic for night use need to be tall to support nods -- which creates problems for most standard BUIS use. Offsets are an option for BUIS, but when you've got a designator, illuminator, white light, and controls for all of that ... plus a holographic sight in play ... the clutter gets crazy quickly (as does the weight).